{"id":"CVE-2026-55428","aliases":["GHSA-wrq8-fcv5-8hvp","GO-2026-5915"],"url":"https://o3.security/vulnerability/CVE-2026-55428","summary":"Coder: Route hijacking through lack of validation of agent-supplied AllowedIPs in tailnet coordinator","details":"Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, the tailnet coordinator validates that an agent's `Addresses` derive from its authenticated UUID but applies no equivalent check to `AllowedIPs`. The coordinator forwards agent-supplied `AllowedIPs` verbatim to tunnel peers which install them into the WireGuard peer configuration. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 validates each `AllowedIPs` prefix against the authenticating agent's UUID just like `Addresses`. As a workaround, monitor coordinator logs for agents advertising unexpected `AllowedIPs` prefixes.","published":"2026-07-07T23:57:45.338Z","modified":"2026-08-12T03:51:15.505719333Z","cvss":{"score":8.2,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N"},"epss":{"score":0.00246,"percentile":0.1619,"asOf":"2026-08-21"},"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/26144","label":"coder/coder#26144"},"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-2026-55428.json"},{"type":"ADVISORY","url":"https://github.com/coder/coder/security/advisories/GHSA-wrq8-fcv5-8hvp"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55428"},{"type":"FIX","url":"https://github.com/coder/coder/pull/26144"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:15.505719333Z"}}