{"id":"GHSA-w7c2-w76w-5hmj","summary":"Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces","details":"### Impact\n\nIn Cilium clusters using [Gateway API](https://docs.cilium.io/en/stable/network/servicemesh/gateway-api/gateway-api/), users with permissions to create or update namespaced HTTPRoutes can mirror HTTP traffic to any Service in any namespace, bypassing the ReferenceGrant authorization mechanism.\n\nGateway API functionality is disabled by default.\n\n### Patches\n\nThis issue affects:\n\n* Cilium v1.19 from v1.19.0 to v1.19.4 inclusive\n* Cilium v1.18 from v1.18.0 to v1.18.10 inclusive\n* All versions of Cilium before v1.17.17\n\nThis issue is patched in:\n\n* Cilium v1.19.5\n* Cilium v1.18.11\n* Cilium v1.17.17\n\n### Workarounds\n\nThere is no workaround to this issue. Users of this feature who are unable to upgrade can mitigate the risk by ensuring that RBAC permissions to create `HTTPRoute` objects are only granted to cluster admins.\n\n### Acknowledgements\n\nThe Cilium community has worked together with members of Isovalent to prepare these mitigations. Special thanks to @galanko for reporting the issue and @mhofstetter for their work on triaging and remediating this issue.\n\n### For more information\n\nIf you have any questions or comments about this advisory, please reach out on [Slack](https://docs.cilium.io/en/latest/community/community/).\n\nIf you think you have found a vulnerability affecting Cilium, we strongly encourage you to report it to our security mailing list at [security@cilium.io](mailto:security@cilium.io). This is a private mailing list for the Cilium security team, and your report will be treated as top priority.","aliases":["BIT-cilium-2026-56742","BIT-cilium-operator-2026-56742","BIT-hubble-relay-2026-56742","CVE-2026-56742"],"modified":"2026-09-24T19:45:04.957835349Z","published":"2026-09-24T19:38:39Z","database_specific":{"github_reviewed_at":"2026-09-24T19:38:39Z","nvd_published_at":"2026-07-15T20:17:51Z","cwe_ids":["CWE-862"],"severity":"MODERATE","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/cilium/cilium/security/advisories/GHSA-w7c2-w76w-5hmj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-56742"},{"type":"WEB","url":"https://github.com/cilium/cilium/commit/7422068aff67ac77c7dcc57aa5b9240c91333deb"},{"type":"WEB","url":"https://github.com/cilium/cilium/commit/e0b1cef513ff910323f3743e9f3e3d86721e4857"},{"type":"WEB","url":"https://github.com/cilium/cilium/commit/f23929cff682d6ed0dc158070812cb302fc0032b"},{"type":"WEB","url":"https://github.com/cilium/cilium/commit/fd47963ea394d5e8fa4a88c40a79063430c512ca"},{"type":"PACKAGE","url":"https://github.com/cilium/cilium"},{"type":"WEB","url":"https://github.com/cilium/cilium/releases/tag/v1.17.17"},{"type":"WEB","url":"https://github.com/cilium/cilium/releases/tag/v1.18.11"},{"type":"WEB","url":"https://github.com/cilium/cilium/releases/tag/v1.19.5"}],"affected":[{"package":{"name":"github.com/cilium/cilium","ecosystem":"Go","purl":"pkg:golang/github.com/cilium/cilium"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"1.17.17"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-w7c2-w76w-5hmj/GHSA-w7c2-w76w-5hmj.json"}},{"package":{"name":"github.com/cilium/ciliumCilium","ecosystem":"Go","purl":"pkg:golang/github.com/cilium/ciliumCilium"},"ranges":[{"type":"SEMVER","events":[{"introduced":"1.18.0"},{"fixed":"1.18.11"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-w7c2-w76w-5hmj/GHSA-w7c2-w76w-5hmj.json"}},{"package":{"name":"github.com/cilium/cilium","ecosystem":"Go","purl":"pkg:golang/github.com/cilium/cilium"},"ranges":[{"type":"SEMVER","events":[{"introduced":"1.19.0"},{"fixed":"1.19.5"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/09/GHSA-w7c2-w76w-5hmj/GHSA-w7c2-w76w-5hmj.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:L"}]}