Auth bypass in Cilium
CVE-2026-56742
Cilium is a networking, observability, and security solution. Prior to 1.17.17, 1.18.11, and 1.19.5, Cilium clusters using Gateway API allow users with permissions to create or update namespaced HTTPRoutes to mirror HTTP traffic to any Service in any namespace, bypassing the ReferenceGrant authorization mechanism. Gateway API functionality is disabled by default. This issue is fixed in versions 1.17.17, 1.18.11, and 1.19.5.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:L.
EPSS exploit prediction
EPSS: 0.002 (6.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 6th percentile — 6.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.002 · change: -0.001
Affected products
- Cilium — versions < 1.17.17, >= 1.18.0, < 1.18.11, >= 1.19.0, < 1.19.5
Weakness classification (CWE)
References
- github.com/cilium/cilium/security/advisories/GHSA-w7c2-w76w-5hmj (Vendor Advisory)
- github.com/cilium/cilium/commit/7422068aff67ac77c7dcc57aa5b9240c91333deb (Patch)
- github.com/cilium/cilium/commit/e0b1cef513ff910323f3743e9f3e3d86721e4857 (Patch)
- github.com/cilium/cilium/commit/f23929cff682d6ed0dc158070812cb302fc0032b (Patch)
- github.com/cilium/cilium/commit/fd47963ea394d5e8fa4a88c40a79063430c512ca (Patch)
- github.com/cilium/cilium/releases/tag/v1.17.17 (Release Notes)
- github.com/cilium/cilium/releases/tag/v1.18.11 (Release Notes)
- github.com/cilium/cilium/releases/tag/v1.19.5 (Release Notes)
Frequently asked questions
- What is CVE-2026-56742?
- CVE-2026-56742 is a medium-severity vulnerability in Cilium, classified under Missing Authorization. CVSS score: 5.9/10. Published 2026-07-15.
- How severe is CVE-2026-56742?
- Medium severity. CVSS v3 base score is 5.9 out of 10.