What’s Vulnerable › Vulnerabilities

CVE-2026-56742: Cilium: Namespaced HTTPRoutes can redirect traffic to other namespaces

• Severity: high (CVSS 8.9 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-07-15 · updated 2026-07-17
• Weakness: CWE-862

Description

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.

Affected products

• cilium: before 1.17.17; from 1.18.0 before 1.18.11; from 1.19.0 before 1.19.5 — fixed in 1.17.17, 1.18.11, 1.19.5

How to fix

Upgrade to a fixed version: cilium 1.17.17, 1.18.11, 1.19.5. Check the vendor advisory for mitigations.

References

• https://github.com/cilium/cilium/commit/7422068aff67ac77c7dcc57aa5b9240c91333deb
• https://github.com/cilium/cilium/commit/e0b1cef513ff910323f3743e9f3e3d86721e4857
• https://github.com/cilium/cilium/commit/f23929cff682d6ed0dc158070812cb302fc0032b
• https://github.com/cilium/cilium/commit/fd47963ea394d5e8fa4a88c40a79063430c512ca
• https://github.com/cilium/cilium/releases/tag/v1.17.17
• https://github.com/cilium/cilium/releases/tag/v1.18.11
• https://github.com/cilium/cilium/releases/tag/v1.19.5
• https://github.com/cilium/cilium/security/advisories/GHSA-w7c2-w76w-5hmj

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