{ "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-2026-31976", "tracking": { "current_release_date": "2026-03-23T11:05:49.785954Z", "generator": { "date": "2026-02-17T15:00:00Z", "engine": { "name": "V.E.L.M.A", "version": "1.7" } }, "id": "CVE-2026-31976", "initial_release_date": "2026-03-11T20:26:54.605881Z", "revision_history": [ { "date": "2026-03-11T20:26:54.605881Z", "number": "1", "summary": "CVE created.| Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (2).| CWES updated (1)." }, { "date": "2026-03-11T20:27:01.895456Z", "number": "2", "summary": "NCSC Score created." }, { "date": "2026-03-11T20:38:57.843323Z", "number": "3", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| Products created (1).| References created (2).| CWES updated (1)." }, { "date": "2026-03-11T20:39:01.053248Z", "number": "4", "summary": "NCSC Score updated." }, { "date": "2026-03-11T22:39:49.792321Z", "number": "5", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (4).| CWES updated (1)." }, { "date": "2026-03-11T22:40:00.726224Z", "number": "6", "summary": "NCSC Score updated." }, { "date": "2026-03-12T14:57:25.130993Z", "number": "7", "summary": "Source created.| CVE status created. (valid)| EPSS created." }, { "date": "2026-03-12T20:38:54.304986Z", "number": "8", "summary": "Unknown change." }, { "date": "2026-03-16T03:17:47.939354Z", "number": "9", "summary": "NCSC Score updated." }, { "date": "2026-03-16T19:25:32.563923Z", "number": "10", "summary": "CVSS created.| Products created (1).| Product Identifiers created (1)." }, { "date": "2026-03-16T19:25:37.936907Z", "number": "11", "summary": "NCSC Score updated." }, { "date": "2026-03-16T21:41:46.810743Z", "number": "12", "summary": "NCSC Score updated." }, { "date": "2026-03-17T01:26:16.292778Z", "number": "13", "summary": "NCSC Score updated." }, { "date": "2026-03-19T15:30:37.770730Z", "number": "14", "summary": "Source created.| CVE status created. (valid)| Description created for source.| CVSS created.| References created (4).| CWES updated (1)." }, { "date": "2026-03-19T15:30:40.421023Z", "number": "15", "summary": "NCSC Score updated." }, { "date": "2026-03-20T09:32:00.153368Z", "number": "16", "summary": "Source connected.| CVE status created. (valid)| EPSS created." } ], "status": "interim", "version": "16" } }, "product_tree": { "branches": [ { "branches": [ { "branches": [ { "category": "product_version_range", "name": "vers:unknown/>=5.38.0|<=6.4.0", "product": { "name": "vers:unknown/>=5.38.0|<=6.4.0", "product_id": "CSAFPID-5830335", "product_identification_helper": { "cpe": "cpe:2.3:a:xygeni:xygeni-action:*:*:*:*:*:*:*:*" } } }, { "category": "product_version_range", "name": "vers:unknown/>=march3|2026|<=march10|2026", "product": { "name": "vers:unknown/>=march3|2026|<=march10|2026", "product_id": "CSAFPID-5798817" } } ], "category": "product_name", "name": "xygeni-action" } ], "category": "vendor", "name": "xygeni" } ] }, "vulnerabilities": [ { "cve": "CVE-2026-31976", "cwe": { "id": "CWE-506", "name": "Embedded Malicious Code" }, "notes": [ { "category": "description", "text": "xygeni-action is the GitHub Action for Xygeni Scanner. On March 3, 2026, an attacker with access to compromised credentials created a series of pull requests (#46, #47, #48) injecting obfuscated shell code into action.yml. The PRs were blocked by branch protection rules and never merged into the main branch. However, the attacker used the compromised GitHub App credentials to move the mutable v5 tag to point at the malicious commit (4bf1d4e19ad81a3e8d4063755ae0f482dd3baf12) from one of the unmerged PRs. This commit remained in the repository's git object store, and any workflow referencing @v5 would fetch and execute it. This is a supply chain compromise via tag poisoning. Any GitHub Actions workflow referencing xygeni/xygeni-action@v5 during the affected window (approximately March 3–10, 2026) executed a C2 implant that granted the attacker arbitrary command execution on the CI runner for up to 180 seconds per workflow run.", "title": "nvd - https://nvd.nist.gov/vuln/detail/CVE-2026-31976" }, { "category": "description", "text": "xygeni-action is the GitHub Action for Xygeni Scanner. On March 3, 2026, an attacker with access to compromised credentials created a series of pull requests (#46, #47, #48) injecting obfuscated shell code into action.yml. The PRs were blocked by branch protection rules and never merged into the main branch. However, the attacker used the compromised GitHub App credentials to move the mutable v5 tag to point at the malicious commit (4bf1d4e19ad81a3e8d4063755ae0f482dd3baf12) from one of the unmerged PRs. This commit remained in the repository's git object store, and any workflow referencing @v5 would fetch and execute it. This is a supply chain compromise via tag poisoning. Any GitHub Actions workflow referencing xygeni/xygeni-action@v5 during the affected window (approximately March 3–10, 2026) executed a C2 implant that granted the attacker arbitrary command execution on the CI runner for up to 180 seconds per workflow run.", "title": "cveprojectv5 - https://www.cve.org/CVERecord?id=CVE-2026-31976" }, { "category": "description", "text": "### Description\n\nOn March 3, 2026, an attacker with access to compromised credentials created a series of pull requests (#46, #47, #48) injecting obfuscated shell code into `action.yml`. The PRs were blocked by branch protection rules and never merged into the main branch.\n\nHowever, the attacker used the compromised GitHub App credentials to move the mutable `v5` tag to point at the malicious commit (`4bf1d4e19ad81a3e8d4063755ae0f482dd3baf12`) from one of the unmerged PRs. This commit remained in the repository's git object store, and any workflow referencing `@v5` would fetch and execute it.\n\nThe malicious code, disguised as a \"scanner version telemetry\" step, operates as follows:\n\n1. Registers the CI runner with a C2 server at `91.214.78.178` (via `security-verify.91.214.78.178.nip.io`), transmitting hostname, username, and OS version.\n2. Polls the C2 server every 2–7 seconds for 180 seconds, receiving and executing arbitrary shell commands via `eval`.\n3. Compresses and base64-encodes command output before exfiltrating it back to the C2 server.\n\nThe implant runs silently in the background alongside the legitimate scan, suppresses all errors, skips TLS certificate verification, and uses randomized polling intervals to evade detection.\n\n### Impact\n\nThis is a supply chain compromise via tag poisoning. Any GitHub Actions workflow referencing `xygeni/xygeni-action@v5` during the affected window (approximately March 3–10, 2026) executed a C2 implant that granted the attacker arbitrary command execution on the CI runner for up to 180 seconds per workflow run.\n\nThe severity is set to Critical based on the potential impact. However, several factors reduce the realized risk: the `v5` tag was primarily referenced by Xygeni-owned and Xygeni-affiliated repositories; no external public repositories were found using the compromised tag (though usage in private repositories cannot be ruled out); the exposure window was approximately 6 days; and no confirmed exploitation of downstream users has been established to date.\n\n### Patches\n\nThe compromised `v5` tag has been removed from the repository. Users should update their workflows to pin to the verified safe commit SHA corresponding to v6.4.0:\n\n```yaml\nuses: xygeni/xygeni-action@13c6ed2797df7d85749864e2cbcf09c893f43b23 # v6.4.0\n```\n\nWorkflows still referencing `@v5` will fail with a reference not found error, as the tag no longer exists.\n\nIf your workflows ran with `@v5` during the affected window, you should also:\n\n- Rotate all secrets that were available to the CI runner (repository secrets, environment secrets, deploy keys, cloud provider tokens).\n- Audit CI logs for outbound connections to `91.214.78.178` or DNS lookups for `security-verify.91.214.78.178.nip.io`.\n- Review recent releases and published artifacts for signs of tampering.\n\n\n### Workarounds\n\nAs an alternative to using the GitHub Action, you may install and run the Xygeni scanner directly via the CLI installation method documented at https://docs.xygeni.io/xygeni-scanner-cli/xygeni-cli-overview/xygeni-cli-installation. This bypasses the GitHub Action entirely and is not affected by this incident.\n\n### References\n\n- GitHub issue: https://github.com/xygeni/xygeni-action/issues/54\n- Xygeni incident blog post: (URL to be added upon publication)", "title": "github - https://github.com/advisories/GHSA-f8q5-h5qh-33mh" }, { "category": "description", "text": "### Description\n\nOn March 3, 2026, an attacker with access to compromised credentials created a series of pull requests (#46, #47, #48) injecting obfuscated shell code into `action.yml`. The PRs were blocked by branch protection rules and never merged into the main branch.\n\nHowever, the attacker used the compromised GitHub App credentials to move the mutable `v5` tag to point at the malicious commit (`4bf1d4e19ad81a3e8d4063755ae0f482dd3baf12`) from one of the unmerged PRs. This commit remained in the repository's git object store, and any workflow referencing `@v5` would fetch and execute it.\n\nThe malicious code, disguised as a \"scanner version telemetry\" step, operates as follows:\n\n1. Registers the CI runner with a C2 server at `91.214.78.178` (via `security-verify.91.214.78.178.nip.io`), transmitting hostname, username, and OS version.\n2. Polls the C2 server every 2–7 seconds for 180 seconds, receiving and executing arbitrary shell commands via `eval`.\n3. Compresses and base64-encodes command output before exfiltrating it back to the C2 server.\n\nThe implant runs silently in the background alongside the legitimate scan, suppresses all errors, skips TLS certificate verification, and uses randomized polling intervals to evade detection.\n\n### Impact\n\nThis is a supply chain compromise via tag poisoning. Any GitHub Actions workflow referencing `xygeni/xygeni-action@v5` during the affected window (approximately March 3–10, 2026) executed a C2 implant that granted the attacker arbitrary command execution on the CI runner for up to 180 seconds per workflow run.\n\nThe severity is set to Critical based on the potential impact. However, several factors reduce the realized risk: the `v5` tag was primarily referenced by Xygeni-owned and Xygeni-affiliated repositories; no external public repositories were found using the compromised tag (though usage in private repositories cannot be ruled out); the exposure window was approximately 6 days; and no confirmed exploitation of downstream users has been established to date.\n\n### Patches\n\nThe compromised `v5` tag has been removed from the repository. Users should update their workflows to pin to the verified safe commit SHA corresponding to v6.4.0:\n\n```yaml\nuses: xygeni/xygeni-action@13c6ed2797df7d85749864e2cbcf09c893f43b23 # v6.4.0\n```\n\nWorkflows still referencing `@v5` will fail with a reference not found error, as the tag no longer exists.\n\nIf your workflows ran with `@v5` during the affected window, you should also:\n\n- Rotate all secrets that were available to the CI runner (repository secrets, environment secrets, deploy keys, cloud provider tokens).\n- Audit CI logs for outbound connections to `91.214.78.178` or DNS lookups for `security-verify.91.214.78.178.nip.io`.\n- Review recent releases and published artifacts for signs of tampering.\n\n\n### Workarounds\n\nAs an alternative to using the GitHub Action, you may install and run the Xygeni scanner directly via the CLI installation method documented at https://docs.xygeni.io/xygeni-scanner-cli/xygeni-cli-overview/xygeni-cli-installation. This bypasses the GitHub Action entirely and is not affected by this incident.\n\n### References\n\n- GitHub issue: https://github.com/xygeni/xygeni-action/issues/54\n- Xygeni incident blog post: (URL to be added upon publication)", "title": "github - https://api.github.com/advisories/GHSA-f8q5-h5qh-33mh" }, { "category": "other", "text": "0.00078", "title": "EPSS" }, { "category": "other", "text": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X", "title": "CVSSV4" }, { "category": "other", "text": "9.3", "title": "CVSSV4 base score" }, { "category": "other", "text": "4.8", "title": "NCSC Score" }, { "category": "other", "text": "There is cvss data available from a private source, There is product data available from a private source", "title": "NCSC Score top increasing factors" }, { "category": "other", "text": "The value of the most recent EPSS score", "title": "NCSC Score top decreasing factors" } ], "product_status": { "known_affected": [ "CSAFPID-5798817", "CSAFPID-5830335" ] }, "references": [ { "category": "external", "summary": "Source - nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31976" }, { "category": "external", "summary": "Source raw - nvd", "url": "https://services.nvd.nist.gov/rest/json/cves/2.0?cveId=CVE-2026-31976" }, { "category": "external", "summary": "Source - cveprojectv5", "url": "https://www.cve.org/CVERecord?id=CVE-2026-31976" }, { "category": "external", "summary": "Source raw - cveprojectv5", "url": "https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/31xxx/CVE-2026-31976.json" }, { "category": "external", "summary": "Source - github", "url": "https://github.com/advisories/GHSA-f8q5-h5qh-33mh" }, { "category": "external", "summary": "Source raw - github", "url": "https://api.github.com/advisories/GHSA-f8q5-h5qh-33mh" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-31976" }, { "category": "external", "summary": "Source raw - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Source - github", "url": "https://api.github.com/advisories/GHSA-f8q5-h5qh-33mh" }, { "category": "external", "summary": "Source - first", "url": "https://api.first.org/data/v1/epss?limit=10000&offset=0" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://github.com/xygeni/xygeni-action/issues/54" }, { "category": "external", "summary": "Reference - cveprojectv5; github; nvd", "url": "https://github.com/xygeni/xygeni-action/security/advisories/GHSA-f8q5-h5qh-33mh" }, { "category": "external", "summary": "Reference - github", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31976" }, { "category": "external", "summary": "Reference - github", "url": "https://github.com/advisories/GHSA-f8q5-h5qh-33mh" } ], "scores": [ { "cvss_v3": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "products": [ "CSAFPID-5798817", "CSAFPID-5830335" ] } ], "title": "CVE-2026-31976" } ] }