{"id":"GHSA-wrq8-fcv5-8hvp","summary":"Coder: Route hijacking through lack of validation of agent-supplied AllowedIPs in tailnet coordinator","details":"### Summary\n\nThe 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.\n\n### Impact\n\nA malicious workspace agent can advertise arbitrary `AllowedIPs` prefixes including another agent's tailnet address. Coder's `ServerTailnet` routes to agents by tailnet IP so an agent that claims a victim's prefix can intercept web terminal and workspace app traffic and serve spoofed content. Exploitation requires an authenticated user with a running workspace and a modified agent binary.\n\n### Patches\n\nThe fix validates each `AllowedIPs` prefix against the authenticating agent's UUID just like `Addresses`.\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\nOperators who cannot upgrade immediately should monitor coordinator logs for agents advertising unexpected `AllowedIPs` prefixes.\n\n### Resources\n\n- Fix: #26144\n\n### Credits\n\nCoder would like to thank Anthropic's Security Team (ANT-2026-22451) for independently disclosing this issue!","aliases":["CVE-2026-55428","GO-2026-5915"],"modified":"2026-07-07T16:11:24.471390886Z","published":"2026-07-06T20:58:30Z","database_specific":{"nvd_published_at":null,"cwe_ids":["CWE-285","CWE-863"],"severity":"HIGH","github_reviewed":true,"github_reviewed_at":"2026-07-06T20:58:30Z"},"references":[{"type":"WEB","url":"https://github.com/coder/coder/security/advisories/GHSA-wrq8-fcv5-8hvp"},{"type":"WEB","url":"https://github.com/coder/coder/pull/26144"},{"type":"PACKAGE","url":"https://github.com/coder/coder"}],"affected":[{"package":{"name":"github.com/coder/coder/v2","ecosystem":"Go","purl":"pkg:golang/github.com/coder/coder/v2"},"ranges":[{"type":"SEMVER","events":[{"introduced":"2.34.0"},{"fixed":"2.34.2"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-wrq8-fcv5-8hvp/GHSA-wrq8-fcv5-8hvp.json"}},{"package":{"name":"github.com/coder/coder/v2","ecosystem":"Go","purl":"pkg:golang/github.com/coder/coder/v2"},"ranges":[{"type":"SEMVER","events":[{"introduced":"2.33.0"},{"fixed":"2.33.8"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-wrq8-fcv5-8hvp/GHSA-wrq8-fcv5-8hvp.json"}},{"package":{"name":"github.com/coder/coder/v2","ecosystem":"Go","purl":"pkg:golang/github.com/coder/coder/v2"},"ranges":[{"type":"SEMVER","events":[{"introduced":"2.30.0"},{"fixed":"2.32.7"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-wrq8-fcv5-8hvp/GHSA-wrq8-fcv5-8hvp.json"}},{"package":{"name":"github.com/coder/coder/v2","ecosystem":"Go","purl":"pkg:golang/github.com/coder/coder/v2"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.29.17"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-wrq8-fcv5-8hvp/GHSA-wrq8-fcv5-8hvp.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N"}]}