{"id":"CVE-2026-55437","aliases":["GHSA-7qw2-f75v-62f7","GO-2026-5919"],"url":"https://o3.security/vulnerability/CVE-2026-55437","summary":"Coder vulnerable to stored HTML injection via workspace agent logs in AgentLogLine component","details":"### Summary\n\nThe `AgentLogLine` dashboard component instantiated `ansi-to-html` without `escapeXML: true` and inserted the result via `dangerouslySetInnerHTML` so HTML embedded in workspace agent log lines was rendered as live markup. Server-side sanitization did not neutralize HTML metacharacters.\n\n> **Note:** Exploitation requires a victim to view attacker-controlled agent logs in the dashboard.\n\n### Impact\n\nA user who could run a workspace could emit arbitrary HTML into agent logs; when another user, including an administrator, viewed the workspace page, it rendered in their session. Content Security Policy blocked inline scripts but an attacker could still inject a `meta refresh` redirect, `style` rules for UI redressing or CSS-based exfiltration or external `img` beacons. This required workspace-owner access and a victim viewing the page.\n\n### Patches\n\nThe fix enables `escapeXML: true` so HTML metacharacters are escaped before DOM insertion.\n\nThe fix was backported to all supported release lines:\n\n| Release line | Patched version |\n|---|---|\n| 2.34 | [v2.34.2](https://github.com/coder/coder/releases/tag/v2.34.2) |\n| 2.33 | [v2.33.8](https://github.com/coder/coder/releases/tag/v2.33.8) |\n| 2.32 | [v2.32.7](https://github.com/coder/coder/releases/tag/v2.32.7) |\n| 2.29 (ESR) | [v2.29.17](https://github.com/coder/coder/releases/tag/v2.29.17) |\n\n### Workarounds\n\nNone.\n\n### Resources\n\n- Fix: #25808\n\n### Credits\n\nCoder would like to thank Anthropic's Security Team (ANT-2026-22449) for independently disclosing this issue!","published":"2026-07-08T00:29:18.268Z","modified":"2026-10-21T02:30:41.863620317Z","cvss":{"score":5.4,"severity":"MEDIUM","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N"},"epss":{"score":0.00316,"percentile":0.2454,"asOf":"2026-09-16"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/coder/coder/v2","fixedVersion":"2.34.2"},{"ecosystem":"Go","name":"github.com/coder/coder/v2","fixedVersion":"2.33.8"},{"ecosystem":"Go","name":"github.com/coder/coder/v2","fixedVersion":"2.32.7"},{"ecosystem":"Go","name":"github.com/coder/coder/v2","fixedVersion":"2.29.17"}],"fix":{"url":"https://github.com/coder/coder/pull/25808","label":"coder/coder#25808"},"references":[{"type":"WEB","url":"https://github.com/coder/coder/releases/tag/v2.29.17"},{"type":"WEB","url":"https://github.com/coder/coder/releases/tag/v2.32.7"},{"type":"WEB","url":"https://github.com/coder/coder/releases/tag/v2.33.8"},{"type":"WEB","url":"https://github.com/coder/coder/releases/tag/v2.34.2"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55437.json"},{"type":"ADVISORY","url":"https://github.com/coder/coder/security/advisories/GHSA-7qw2-f75v-62f7"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55437"},{"type":"FIX","url":"https://github.com/coder/coder/pull/25808"},{"type":"PACKAGE","url":"https://github.com/coder/coder"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-10-21T02:30:41.863620317Z"}}