{ "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-2026-27857", "tracking": { "current_release_date": "2026-03-31T15:17:49.529450Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-27857", "initial_release_date": "2026-03-27T08:38:51.712507Z", "revision_history": [ { "date": "2026-03-27T08:38:51.712507Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (1).| References created (1).| CWES updated (1)." }, { "date": "2026-03-27T08:38:56.228398Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-03-27T09:25:05.526593Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (1).| CWES updated (1)." }, { "date": "2026-03-27T09:25:10.714271Z", "number": "4", "summary": "NCSC Score updated." }, { "date": "2026-03-27T11:11:05.385402Z", "number": "5", "summary": "Source connected.| CVE status created. (valid)| Products connected (2).| References created (3)." }, { "date": "2026-03-27T11:11:10.446488Z", "number": "6", "summary": "NCSC Score updated." }, { "date": "2026-03-27T11:34:50.360818Z", "number": "7", "summary": "NCSC Score updated." }, { "date": "2026-03-27T19:42:19.610217Z", "number": "8", "summary": "Unknown change." }, { "date": "2026-03-27T19:42:23.111410Z", "number": "9", "summary": "NCSC Score updated." }, { "date": "2026-03-27T21:06:33.619120Z", "number": "10", "summary": "Source connected.| CVE status created. (valid)| EPSS created." }, { "date": "2026-03-27T21:06:36.829707Z", "number": "11", "summary": "NCSC Score updated." }, { "date": "2026-03-28T07:41:29.323981Z", "number": "12", "summary": "Source created.| CVE status created. (valid)| Products connected (2)." }, { "date": "2026-03-28T07:41:30.999271Z", "number": "13", "summary": "NCSC Score updated." }, { "date": "2026-03-28T07:42:05.331492Z", "number": "14", "summary": "Description created for source." }, { "date": "2026-03-28T12:28:44.179877Z", "number": "15", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products connected (10).| Product Identifiers created (5).| Product Remediations created (10).| References created (3).| CWES updated (1).| Vendor_assessment created." }, { "date": "2026-03-28T12:28:46.700732Z", "number": "16", "summary": "NCSC Score updated." }, { "date": "2026-03-31T11:09:48.714598Z", "number": "17", "summary": "Products connected (1).| References created (1)." }, { "date": "2026-03-31T11:09:53.332669Z", "number": "18", "summary": "NCSC Score updated." } ], "status": "interim", "version": "18" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/<2.4.0", "product": { "name": "vers:unknown/<2.4.0", "product_id": "CSAFPID-5937944" } }, { "category": "product_version_range", "name": "vers:unknown/<2.4.3", "product": { "name": "vers:unknown/<2.4.3", "product_id": "CSAFPID-5937945" } } ], "category": "product_name", "name": "Dovecot" } ], "category": "vendor", "name": "Open Source" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:semver/<=2.3.0", "product": { "name": "vers:semver/<=2.3.0", "product_id": "CSAFPID-5924462" } } ], "category": "product_name", "name": "OX Dovecot Pro" } ], "category": "vendor", "name": "Open-Xchange GmbH" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:rpm/10", "product": { "name": "vers:rpm/10", "product_id": "CSAFPID-2858634", "product_identification_helper": { "cpe": "cpe:/o:redhat:enterprise_linux:10" } } } ], "category": "product_name", "name": "Red Hat Enterprise Linux 10" }, { "branches": [ { "category": "product_version_range", "name": "vers:rpm/6", "product": { "name": "vers:rpm/6", "product_id": "CSAFPID-1439321", "product_identification_helper": { "cpe": "cpe:/o:redhat:enterprise_linux:6" } } } ], "category": "product_name", "name": "Red Hat Enterprise Linux 6" }, { "branches": [ { "category": "product_version_range", "name": "vers:rpm/7", "product": { "name": "vers:rpm/7", "product_id": "CSAFPID-1439315", "product_identification_helper": { "cpe": "cpe:/o:redhat:enterprise_linux:7" } } } ], "category": "product_name", "name": "Red Hat Enterprise Linux 7" }, { "branches": [ { "category": "product_version_range", "name": "vers:rpm/8", "product": { "name": "vers:rpm/8", "product_id": "CSAFPID-1439317", "product_identification_helper": { "cpe": "cpe:/o:redhat:enterprise_linux:8" } } } ], "category": "product_name", "name": "Red Hat Enterprise Linux 8" }, { "branches": [ { "category": "product_version_range", "name": "vers:rpm/9", "product": { "name": "vers:rpm/9", "product_id": "CSAFPID-1439319", "product_identification_helper": { "cpe": "cpe:/a:redhat:enterprise_linux:9" } } } ], "category": "product_name", "name": "Red Hat Enterprise Linux 9" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:rpm/unknown", "product": { "name": "vers:rpm/unknown", "product_id": "CSAFPID-5958201" } } ], "category": "product_name", "name": "dovecot" } ], "category": "product_family", "name": "Red Hat Enterprise Linux 10" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:rpm/unknown", "product": { "name": "vers:rpm/unknown", "product_id": "CSAFPID-5958202" } } ], "category": "product_name", "name": "dovecot" } ], "category": "product_family", "name": "Red Hat Enterprise Linux 6" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:rpm/unknown", "product": { "name": "vers:rpm/unknown", "product_id": "CSAFPID-5958203" } } ], "category": "product_name", "name": "dovecot" } ], "category": "product_family", "name": "Red Hat Enterprise Linux 7" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:rpm/unknown", "product": { "name": "vers:rpm/unknown", "product_id": "CSAFPID-5958204" } } ], "category": "product_name", "name": "dovecot" } ], "category": "product_family", "name": "Red Hat Enterprise Linux 8" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:rpm/unknown", "product": { "name": "vers:rpm/unknown", "product_id": "CSAFPID-5958205" } } ], "category": "product_name", "name": "dovecot" } ], "category": "product_family", "name": "Red Hat Enterprise Linux 9" } ], "category": "vendor", "name": "Red Hat" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/unknown", "product": { "name": "vers:unknown/unknown", "product_id": "CSAFPID-1317176", "product_identification_helper": { "cpe": "cpe:/o:suse:opensuse:-" } } } ], "category": "product_name", "name": "SUSE openSUSE" } ], "category": "vendor", "name": "SUSE" }, { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:deb/unknown", "product": { "name": "vers:deb/unknown", "product_id": "CSAFPID-1411598" } } ], "category": "product_name", "name": "dovecot" } ], "category": "product_family", "name": "bookworm" }, { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:deb/unknown", "product": { "name": "vers:deb/unknown", "product_id": "CSAFPID-1411534" } } ], "category": "product_name", "name": "dovecot" } ], "category": "product_family", "name": "bullseye" } ], "category": "vendor", "name": "Debian" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-27857", "cwe": { "id": "CWE-770", "name": "Allocation of Resources Without Limits or Throttling" }, "notes": [ { "category": "description", "text": "Sending \"NOOP (((...)))\" command with 4000 parenthesis open+close results in ~1MB extra memory usage. Longer commands will result in client disconnection. This 1 MB can be left allocated for longer time periods by not sending the command ending LF. So attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Install fixed version, there is no other remediation. No publicly available exploits are known.", "title": "cveprojectv5 - https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/27xxx/CVE-2026-27857.json" }, { "category": "description", "text": "Sending \"NOOP (((...)))\" command with 4000 parenthesis open+close results in ~1MB extra memory usage. Longer commands will result in client disconnection. This 1 MB can be left allocated for longer time periods by not sending the command ending LF. So attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Install fixed version, there is no other remediation. No publicly available exploits are known.", "title": "nvd - https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-27857" }, { "category": "description", "text": "Sending \"NOOP (((...)))\" command with 4000 parenthesis open+close results in ~1MB extra memory usage. Longer commands will result in client disconnection. This 1 MB can be left allocated for longer time periods by not sending the command ending LF. So attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Install fixed version, there is no other remediation. No publicly available exploits are known.", "title": "debian - https://security-tracker.debian.org/tracker/CVE-2026-27857" }, { "category": "description", "text": "Sending \"NOOP (((...)))\" command with 4000 parenthesis open+close results in ~1MB extra memory usage. Longer commands will result in client disconnection. This 1 MB can be left allocated for longer time periods by not sending the command ending LF. So attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Install fixed version, there is no other remediation. No publicly available exploits are known.\nA flaw was found in dovecot. An unauthenticated and remote attacker can send a specially crafted \"NOOP\" command containing numerous open and close parentheses without a command-ending line feed, causing the server to allocate an excessive amount of memory, resulting in a denial of service.\nThis flaw allows an unauthenticated and remote attacker to cause a denial of service via a specially crafted \"NOOP\" command. Due to this reason, this vulnerability has been rated with an important severity.", "title": "redhat - https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-27857.json" }, { "category": "other", "text": "0.00039", "title": "EPSS" }, { "category": "other", "text": "3.8", "title": "NCSC Score" }, { "category": "other", "text": "There is product data available from source Certbundde", "title": "NCSC Score top increasing factors" }, { "category": "other", "text": "There is product data available from source Debian, Is related to (a version of) an uncommon product, Is related to an uncommon product vendor", "title": "NCSC Score top decreasing factors" }, { "category": "details", "text": "Severity: 3\n", "title": "Vendor assessment" } ], "product_status": { "known_affected": [ "CSAFPID-5924462", "CSAFPID-5937944", "CSAFPID-5937945", "CSAFPID-1411534", "CSAFPID-1411598", "CSAFPID-1439315", "CSAFPID-1439317", "CSAFPID-1439319", "CSAFPID-1439321", "CSAFPID-2858634", "CSAFPID-5958201", "CSAFPID-5958202", "CSAFPID-5958203", "CSAFPID-5958204", "CSAFPID-5958205", "CSAFPID-1317176" ] }, "references": [ { "category": "external", "summary": "Source - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/27xxx/CVE-2026-27857.json" }, { "category": "external", "summary": "Source - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-27857" }, { "category": "external", "summary": "Source - certbundde", "url": "https://wid.cert-bund.de/.well-known/csaf/white/2026/wid-sec-w-2026-0891.json" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Source - debian", "url": "https://security-tracker.debian.org/tracker/CVE-2026-27857" }, { "category": "external", "summary": "Source - redhat", "url": "https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2026-27857.json" }, { "category": "external", "summary": "Reference - cveprojectv5; nvd; redhat", "url": "https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json" }, { "category": "external", "summary": "Reference - certbundde", "url": "https://wid.cert-bund.de/.well-known/csaf/white/2026/wid-sec-w-2026-0891.json" }, { "category": "external", "summary": "Reference - certbundde", "url": "https://wid.cert-bund.de/portal/wid/securityadvisory?name=WID-SEC-2026-0891" }, { "category": "external", "summary": "Reference - certbundde", "url": "https://dovecot.org/mailman3/archives/list/dovecot@dovecot.org/thread/I4KFFV4IKP6M5MS67SWYHKDSDMSNILQG/" }, { "category": "external", "summary": "Reference - redhat", "url": "https://www.cve.org/CVERecord?id=CVE-2026-27857" }, { "category": "external", "summary": "Reference - redhat", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27857" }, { "category": "external", "summary": "Reference - certbundde", "url": "https://lists.opensuse.org/archives/list/security-announce@lists.opensuse.org/thread/OBSVSMBRLSXDJ3TFA22MX7UVQIY2WIIN/" } ], "remediations": [ { "category": "mitigation", "details": "Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible.", "product_ids": [ "CSAFPID-1439315", "CSAFPID-1439317", "CSAFPID-1439319", "CSAFPID-1439321", "CSAFPID-2858634", "CSAFPID-5958201", "CSAFPID-5958202", "CSAFPID-5958203", "CSAFPID-5958204", "CSAFPID-5958205" ] } ], "scores": [ { "cvss_v3": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "products": [ "CSAFPID-1317176", "CSAFPID-1411534", "CSAFPID-1411598", "CSAFPID-1439315", "CSAFPID-1439317", "CSAFPID-1439319", "CSAFPID-1439321", "CSAFPID-2858634", "CSAFPID-5924462", "CSAFPID-5937944", "CSAFPID-5937945", "CSAFPID-5958201", "CSAFPID-5958202", "CSAFPID-5958203", "CSAFPID-5958204", "CSAFPID-5958205" ] } ], "title": "CVE-2026-27857" } ] }