{ "document": { "category": "csaf_base", "csaf_version": "2.0", "distribution": { "tlp": { "label": "WHITE" } }, "lang": "en", "notes": [ { "category": "legal_disclaimer", "text": "The Netherlands Cyber Security Center (henceforth: NCSC-NL) maintains this portal to enhance access to its information and vulnerabilities. The use of this information is subject to the following terms and conditions:\n\nThe vulnerabilities disclosed in this portal are gathered by NCSC-NL from a variety of open sources, which the user can retrieve from other platforms. NCSC-NL makes every reasonable effort to ensure that the content of this portal is kept up to date, and that it is accurate and complete. Nevertheless, NCSC-NL cannot entirely rule out the possibility of errors, and therefore cannot give any warranty in respect of its completeness, accuracy or real-time keeping up-to-date. NCSC-NL does not control nor guarantee the accuracy, relevance, timeliness or completeness of information obtained from these external sources. The vulnerabilities disclosed in this portal are intended solely for the convenience of professional parties to take appropriate measures to manage the risks posed to the cybersecurity. No rights can be derived from the information provided therein.\n\nNCSC-NL and the Kingdom of the Netherlands assume no legal liability or responsibility for any damage resulting from either the use or inability of use of the vulnerabilities disclosed in this portal. This includes damage resulting from the inaccuracy of incompleteness of the information contained in it.\nThe information on this page is subject to Dutch law. All disputes related to or arising from the use of this portal regarding the disclosure of vulnerabilities will be submitted to the competent court in The Hague. This choice of means also applies to the court in summary proceedings." } ], "publisher": { "category": "coordinator", "contact_details": "cert@ncsc.nl", "name": "National Cyber Security Centre", "namespace": "https://www.ncsc.nl/" }, "title": "CVE-2026-26994", "tracking": { "current_release_date": "2026-03-20T09:42:56.410406Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-26994", "initial_release_date": "2026-02-19T06:12:39.482686Z", "revision_history": [ { "date": "2026-02-19T06:12:39.482686Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (4).| CWES updated (1)." }, { "date": "2026-02-19T06:12:39.854027Z", "number": "2", "summary": "Source created.| CVE status created. (valid)| Description created for source.| References created (4)." }, { "date": "2026-02-19T06:12:47.623169Z", "number": "3", "summary": "NCSC Score created." }, { "date": "2026-02-19T18:47:52.896072Z", "number": "4", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (7).| CWES updated (1)." }, { "date": "2026-02-20T03:24:58.591523Z", "number": "5", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (4).| CWES updated (1)." }, { "date": "2026-02-20T03:25:05.755686Z", "number": "6", "summary": "NCSC Score updated." }, { "date": "2026-02-20T03:38:44.693967Z", "number": "7", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (4).| CWES updated (1)." }, { "date": "2026-02-20T03:38:55.137872Z", "number": "8", "summary": "NCSC Score updated." }, { "date": "2026-02-20T07:35:02.505144Z", "number": "9", "summary": "NCSC Score updated." }, { "date": "2026-02-20T14:13:29.847336Z", "number": "10", "summary": "Source created.| CVE status created. (valid)| EPSS created." }, { "date": "2026-02-20T15:50:41.685650Z", "number": "11", "summary": "Unknown change." }, { "date": "2026-02-20T19:29:12.429580Z", "number": "12", "summary": "Products connected (1).| Product Identifiers created (1)." }, { "date": "2026-02-20T19:29:18.540227Z", "number": "13", "summary": "NCSC Score updated." }, { "date": "2026-02-21T00:55:22.629787Z", "number": "14", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (23).| Products connected (8).| References created (6).| CWES updated (1)." }, { "date": "2026-02-21T00:55:26.385198Z", "number": "15", "summary": "NCSC Score updated." }, { "date": "2026-02-23T00:12:32.919864Z", "number": "16", "summary": "References created (1)." }, { "date": "2026-02-23T00:42:55.261791Z", "number": "17", "summary": "Source created.| CVE status created. (valid)| Description created for source.| Products created (2)." }, { "date": "2026-02-23T00:42:57.440196Z", "number": "18", "summary": "NCSC Score updated." }, { "date": "2026-03-19T10:38:56.848727Z", "number": "19", "summary": "Products created (2)." }, { "date": "2026-03-20T09:42:52.385028Z", "number": "20", "summary": "Source connected.| CVE status created. (valid)| EPSS created." }, { "date": "2026-03-20T09:42:54.889556Z", "number": "21", "summary": "NCSC Score updated." } ], "status": "interim", "version": "21" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/1.7.0", "product": { "name": "vers:unknown/1.7.0", "product_id": "CSAFPID-5849998" } }, { "category": "product_version_range", "name": "vers:unknown/<1.7.0", "product": { "name": "vers:unknown/<1.7.0", "product_id": "CSAFPID-5849999" } } ], "category": "product_name", "name": "go/github.com/refraction-networking/utls" }, { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<1.7.0", "product": { "name": "vers:unknown/<1.7.0", "product_id": "CSAFPID-5643601", "product_identification_helper": { "cpe": "cpe:2.3:a:refraction-networking:utls:*:*:*:*:*:go:*:*" } } }, { "category": "product_version_range", "name": "vers:unknown/>=0|<1.7.0", "product": { "name": "vers:unknown/>=0|<1.7.0", "product_id": "CSAFPID-5632918" } }, { "category": "product_version_range", "name": "vers:unknown/v1.0.0", "product": { "name": "vers:unknown/v1.0.0", "product_id": "CSAFPID-5656546" } }, { "category": "product_version_range", "name": "vers:unknown/v1.1.0", "product": { "name": "vers:unknown/v1.1.0", "product_id": "CSAFPID-5656547" } }, { "category": "product_version_range", "name": "vers:unknown/v1.1.1", "product": { "name": "vers:unknown/v1.1.1", "product_id": "CSAFPID-5656548" } }, { "category": "product_version_range", "name": "vers:unknown/v1.1.2", "product": { "name": "vers:unknown/v1.1.2", "product_id": "CSAFPID-5656549" } }, { "category": "product_version_range", "name": "vers:unknown/v1.1.3", "product": { "name": "vers:unknown/v1.1.3", "product_id": "CSAFPID-5656550" } }, { "category": "product_version_range", "name": "vers:unknown/v1.1.4", "product": { "name": "vers:unknown/v1.1.4", "product_id": "CSAFPID-5656551" } }, { "category": "product_version_range", "name": "vers:unknown/v1.1.5", "product": { "name": "vers:unknown/v1.1.5", "product_id": "CSAFPID-5656552" } }, { "category": "product_version_range", "name": "vers:unknown/v1.2.0", "product": { "name": "vers:unknown/v1.2.0", "product_id": "CSAFPID-5656553" } }, { "category": "product_version_range", "name": "vers:unknown/v1.2.1", "product": { "name": "vers:unknown/v1.2.1", "product_id": "CSAFPID-5656554" } }, { "category": "product_version_range", "name": "vers:unknown/v1.2.2", "product": { "name": "vers:unknown/v1.2.2", "product_id": "CSAFPID-5656555" } }, { "category": "product_version_range", "name": "vers:unknown/v1.3.0", "product": { "name": "vers:unknown/v1.3.0", "product_id": "CSAFPID-5656556" } }, { "category": "product_version_range", "name": "vers:unknown/v1.3.1", "product": { "name": "vers:unknown/v1.3.1", "product_id": "CSAFPID-5656557" } }, { "category": "product_version_range", "name": "vers:unknown/v1.3.2", "product": { "name": "vers:unknown/v1.3.2", "product_id": "CSAFPID-5656558" } }, { "category": "product_version_range", "name": "vers:unknown/v1.3.3", "product": { "name": "vers:unknown/v1.3.3", "product_id": "CSAFPID-5656559" } }, { "category": "product_version_range", "name": "vers:unknown/v1.4.0", "product": { "name": "vers:unknown/v1.4.0", "product_id": "CSAFPID-5656560" } }, { "category": "product_version_range", "name": "vers:unknown/v1.4.1", "product": { "name": "vers:unknown/v1.4.1", "product_id": "CSAFPID-5656561" } }, { "category": "product_version_range", "name": "vers:unknown/v1.4.2", "product": { "name": "vers:unknown/v1.4.2", "product_id": "CSAFPID-5656562" } }, { "category": "product_version_range", "name": "vers:unknown/v1.4.3", "product": { "name": "vers:unknown/v1.4.3", "product_id": "CSAFPID-5656563" } }, { "category": "product_version_range", "name": "vers:unknown/v1.5.0", "product": { "name": "vers:unknown/v1.5.0", "product_id": "CSAFPID-5656564" } }, { "category": "product_version_range", "name": "vers:unknown/v1.5.1", "product": { "name": "vers:unknown/v1.5.1", "product_id": "CSAFPID-5656565" } }, { "category": "product_version_range", "name": "vers:unknown/v1.5.2", "product": { "name": "vers:unknown/v1.5.2", "product_id": "CSAFPID-5656566" } }, { "category": "product_version_range", "name": "vers:unknown/v1.5.3", "product": { "name": "vers:unknown/v1.5.3", "product_id": "CSAFPID-5656567" } }, { "category": "product_version_range", "name": "vers:unknown/v1.5.4", "product": { "name": "vers:unknown/v1.5.4", "product_id": "CSAFPID-5656568" } }, { "category": "product_version_range", "name": "vers:unknown/v1.6.0", "product": { "name": "vers:unknown/v1.6.0", "product_id": "CSAFPID-5656109" } }, { "category": "product_version_range", "name": "vers:unknown/v1.6.1", "product": { "name": "vers:unknown/v1.6.1", "product_id": "CSAFPID-5656110" } }, { "category": "product_version_range", "name": "vers:unknown/v1.6.2", "product": { "name": "vers:unknown/v1.6.2", "product_id": "CSAFPID-5656111" } }, { "category": "product_version_range", "name": "vers:unknown/v1.6.3", "product": { "name": "vers:unknown/v1.6.3", "product_id": "CSAFPID-5656112" } }, { "category": "product_version_range", "name": "vers:unknown/v1.6.4", "product": { "name": "vers:unknown/v1.6.4", "product_id": "CSAFPID-5656113" } }, { "category": "product_version_range", "name": "vers:unknown/v1.6.5", "product": { "name": "vers:unknown/v1.6.5", "product_id": "CSAFPID-5656114" } }, { "category": "product_version_range", "name": "vers:unknown/v1.6.6", "product": { "name": "vers:unknown/v1.6.6", "product_id": "CSAFPID-5656115" } }, { "category": "product_version_range", "name": "vers:unknown/v1.6.7", "product": { "name": "vers:unknown/v1.6.7", "product_id": "CSAFPID-5656116" } } ], "category": "product_name", "name": "utls" } ], "category": "vendor", "name": "refraction-networking" }, { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:deb/unknown", "product": { "name": "vers:deb/unknown", "product_id": "CSAFPID-5667939" } } ], "category": "product_name", "name": "golang-refraction-networking-utls" } ], "category": "product_family", "name": "bookworm" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:deb/unknown", "product": { "name": "vers:deb/unknown", "product_id": "CSAFPID-5667940" } } ], "category": "product_name", "name": "golang-refraction-networking-utls" } ], "category": "product_family", "name": "bullseye" } ], "category": "vendor", "name": "debian" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-26994", "notes": [ { "category": "description", "text": "### Description\nBefore version 1.7.0, utls did not implement the TLS 1.3 downgrade protection mechanism specified in RFC 8446 Section 4.1.3 when using a utls ClientHello spec. This allowed an active network adversary to downgrade TLS 1.3 connections initiated by a utls client to a lower TLS version (e.g., TLS 1.2) by modifying the ClientHello message to exclude the SupportedVersions extension, causing the server to respond with a TLS 1.2 ServerHello (along with a downgrade canary in the ServerHello random field). Because utls did not check the downgrade canary in the ServerHello random field, clients would accept the downgraded connection without detecting the attack. This attack could also be used by an active network attacker to fingerprint utls connections.\n\n### Fix Commit or Pull Request\n\nrefraction-networking/utls#337, specifically refraction-networking/utls@f8892761e2a4d29054264651d3a86fda83bc83f9\n\n### References\n\n- https://github.com/refraction-networking/utls/issues/181", "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGHSA-pmc3-p9hx-jq96.json?alt=media" }, { "category": "description", "text": "Before version 1.7.0, utls did not implement the TLS 1.3 downgrade protection mechanism specified in RFC 8446 Section 4.1.3 when using a utls ClientHello spec. This allowed an active network adversary to downgrade TLS 1.3 connections initiated by a utls client to a lower TLS version (e.g., TLS 1.2) by modifying the ClientHello message to exclude the SupportedVersions extension, causing the server to respond with a TLS 1.2 ServerHello (along with a downgrade canary in the ServerHello random field). Because utls did not check the downgrade canary in the ServerHello random field, clients would accept the downgraded connection without detecting the attack. This attack could also be used by an active network attacker to fingerprint utls connections.", "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGO-2025-3638.json?alt=media" }, { "category": "description", "text": "Before version 1.7.0, utls did not implement the TLS 1.3 downgrade protection mechanism specified in RFC 8446 Section 4.1.3 when using a utls ClientHello spec. This allowed an active network adversary to downgrade TLS 1.3 connections initiated by a utls client to a lower TLS version (e.g., TLS 1.2) by modifying the ClientHello message to exclude the SupportedVersions extension, causing the server to respond with a TLS 1.2 ServerHello (along with a downgrade canary in the ServerHello random field). Because utls did not check the downgrade canary in the ServerHello random field, clients would accept the downgraded connection without detecting the attack. This attack could also be used by an active network attacker to fingerprint utls connections.", "title": "gitlab - https://gitlab.com/api/v4/projects/25847700/repository/files/go%2Fgithub.com%2Frefraction-networking%2Futls%2FCVE-2026-26994.yml/raw" }, { "category": "description", "text": "uTLS is a fork of crypto/tls, created to customize ClientHello for fingerprinting resistance while still using it for the handshake. In versions 1.6.7 and below, uTLS did not implement the TLS 1.3 downgrade protection mechanism specified in RFC 8446 Section 4.1.3 when using a uTLS ClientHello spec. This allowed an active network adversary to downgrade TLS 1.3 connections initiated by a uTLS client to a lower TLS version (e.g., TLS 1.2) by modifying the ClientHello message to exclude the SupportedVersions extension, causing the server to respond with a TLS 1.2 ServerHello (along with a downgrade canary in the ServerHello random field). Because uTLS did not check the downgrade canary in the ServerHello random field, clients would accept the downgraded connection without detecting the attack. This attack could also be used by an active network attacker to fingerprint uTLS connections. This issue has been fixed in version 1.7.0.", "title": "nvd - https://nvd.nist.gov/vuln/detail/CVE-2026-26994" }, { "category": "description", "text": "uTLS is a fork of crypto/tls, created to customize ClientHello for fingerprinting resistance while still using it for the handshake. In versions 1.6.7 and below, uTLS did not implement the TLS 1.3 downgrade protection mechanism specified in RFC 8446 Section 4.1.3 when using a uTLS ClientHello spec. This allowed an active network adversary to downgrade TLS 1.3 connections initiated by a uTLS client to a lower TLS version (e.g., TLS 1.2) by modifying the ClientHello message to exclude the SupportedVersions extension, causing the server to respond with a TLS 1.2 ServerHello (along with a downgrade canary in the ServerHello random field). Because uTLS did not check the downgrade canary in the ServerHello random field, clients would accept the downgraded connection without detecting the attack. This attack could also be used by an active network attacker to fingerprint uTLS connections. This issue has been fixed in version 1.7.0.", "title": "cveprojectv5 - https://www.cve.org/CVERecord?id=CVE-2026-26994" }, { "category": "description", "text": "uTLS is a fork of crypto/tls, created to customize ClientHello for fingerprinting resistance while still using it for the handshake. In versions 1.6.7 and below, uTLS did not implement the TLS 1.3 downgrade protection mechanism specified in RFC 8446 Section 4.1.3 when using a uTLS ClientHello spec. This allowed an active network adversary to downgrade TLS 1.3 connections initiated by a uTLS client to a lower TLS version (e.g., TLS 1.2) by modifying the ClientHello message to exclude the SupportedVersions extension, causing the server to respond with a TLS 1.2 ServerHello (along with a downgrade canary in the ServerHello random field). Because uTLS did not check the downgrade canary in the ServerHello random field, clients would accept the downgraded connection without detecting the attack. This attack could also be used by an active network attacker to fingerprint uTLS connections. This issue has been fixed in version 1.7.0.", "title": "osv - https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/GIT%2FCVE-2026-26994.json?alt=media" }, { "category": "description", "text": "uTLS is a fork of crypto/tls, created to customize ClientHello for fingerprinting resistance while still using it for the handshake. In versions 1.6.7 and below, uTLS did not implement the TLS 1.3 downgrade protection mechanism specified in RFC 8446 Section 4.1.3 when using a uTLS ClientHello spec. This allowed an active network adversary to downgrade TLS 1.3 connections initiated by a uTLS client to a lower TLS version (e.g., TLS 1.2) by modifying the ClientHello message to exclude the SupportedVersions extension, causing the server to respond with a TLS 1.2 ServerHello (along with a downgrade canary in the ServerHello random field). Because uTLS did not check the downgrade canary in the ServerHello random field, clients would accept the downgraded connection without detecting the attack. This attack could also be used by an active network attacker to fingerprint uTLS connections. This issue has been fixed in version 1.7.0.", "title": "debian - https://security-tracker.debian.org/tracker/CVE-2026-26994" }, { "category": "other", "text": "0.00014", "title": "EPSS" }, { "category": "other", "text": "4.3", "title": "NCSC Score" }, { "category": "other", "text": "The value of the most recent EPSS score", "title": "NCSC Score top decreasing factors" } ], "product_status": { "fixed": [ "CSAFPID-5849998" ], "known_affected": [ "CSAFPID-5632918", "CSAFPID-5643601", "CSAFPID-5656109", "CSAFPID-5656110", "CSAFPID-5656111", "CSAFPID-5656112", "CSAFPID-5656113", "CSAFPID-5656114", "CSAFPID-5656115", "CSAFPID-5656116", "CSAFPID-5656546", "CSAFPID-5656547", "CSAFPID-5656548", "CSAFPID-5656549", "CSAFPID-5656550", "CSAFPID-5656551", "CSAFPID-5656552", "CSAFPID-5656553", "CSAFPID-5656554", "CSAFPID-5656555", "CSAFPID-5656556", "CSAFPID-5656557", "CSAFPID-5656558", "CSAFPID-5656559", "CSAFPID-5656560", "CSAFPID-5656561", "CSAFPID-5656562", "CSAFPID-5656563", "CSAFPID-5656564", "CSAFPID-5656565", "CSAFPID-5656566", "CSAFPID-5656567", "CSAFPID-5656568", "CSAFPID-5667939", "CSAFPID-5667940", "CSAFPID-5849999" ] }, "references": [ { "category": "external", "summary": "Source - osv", "url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGHSA-pmc3-p9hx-jq96.json?alt=media" }, { "category": "external", "summary": "Source - osv", "url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/Go%2FGO-2025-3638.json?alt=media" }, { "category": "external", "summary": "Source - gitlab", "url": "https://gitlab.com/api/v4/projects/25847700/repository/files/go%2Fgithub.com%2Frefraction-networking%2Futls%2FCVE-2026-26994.yml/raw" }, { "category": "external", "summary": "Source - nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-26994" }, { "category": "external", "summary": "Source raw - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-26994" }, { "category": "external", "summary": "Source - cveprojectv5", "url": "https://www.cve.org/CVERecord?id=CVE-2026-26994" }, { "category": "external", "summary": "Source raw - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/26xxx/CVE-2026-26994.json" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-26994" }, { "category": "external", "summary": "Source raw - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Source - osv", "url": "https://www.googleapis.com/download/storage/v1/b/osv-vulnerabilities/o/GIT%2FCVE-2026-26994.json?alt=media" }, { "category": "external", "summary": "Source - debian", "url": "https://security-tracker.debian.org/tracker/CVE-2026-26994" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Reference - cveprojectv5; gitlab; nvd; osv", "url": "https://github.com/refraction-networking/utls/security/advisories/GHSA-pmc3-p9hx-jq96" }, { "category": "external", "summary": "Reference - cveprojectv5; gitlab; nvd; osv", "url": "https://github.com/refraction-networking/utls/issues/181" }, { "category": "external", "summary": "Reference - cveprojectv5; gitlab; nvd; osv", "url": "https://github.com/refraction-networking/utls/pull/337" }, { "category": "external", "summary": "Reference - cveprojectv5; gitlab; nvd; osv", "url": "https://github.com/refraction-networking/utls/commit/f8892761e2a4d29054264651d3a86fda83bc83f9" }, { "category": "external", "summary": "Reference - gitlab; osv", "url": "https://github.com/advisories/GHSA-pmc3-p9hx-jq96" }, { "category": "external", "summary": "Reference - gitlab; osv", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-26994" }, { "category": "external", "summary": "Reference - gitlab", "url": "https://github.com/refraction-networking/utls" }, { "category": "external", "summary": "Reference - osv", "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/26xxx/CVE-2026-26994.json" } ], "scores": [ { "cvss_v3": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N", "baseScore": 6.5, "baseSeverity": "MEDIUM" }, "products": [ "CSAFPID-5632918", "CSAFPID-5643601", "CSAFPID-5656109", "CSAFPID-5656110", "CSAFPID-5656111", "CSAFPID-5656112", "CSAFPID-5656113", "CSAFPID-5656114", "CSAFPID-5656115", "CSAFPID-5656116", "CSAFPID-5656546", "CSAFPID-5656547", "CSAFPID-5656548", "CSAFPID-5656549", "CSAFPID-5656550", "CSAFPID-5656551", "CSAFPID-5656552", "CSAFPID-5656553", "CSAFPID-5656554", "CSAFPID-5656555", "CSAFPID-5656556", "CSAFPID-5656557", "CSAFPID-5656558", "CSAFPID-5656559", "CSAFPID-5656560", "CSAFPID-5656561", "CSAFPID-5656562", "CSAFPID-5656563", "CSAFPID-5656564", "CSAFPID-5656565", "CSAFPID-5656566", "CSAFPID-5656567", "CSAFPID-5656568", "CSAFPID-5667939", "CSAFPID-5667940", "CSAFPID-5849999" ] } ], "title": "CVE-2026-26994" } ] }