Missing Authorization in Cilium - CVE-2026-56742
Published: November 9, 2026
Vulnerability identifier: #VU162616
CSH Severity: Low
CVSS v4: 4.8 [CVSS:4.0/AV:A/AC:L/AT:N/PR:H/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-56742
CWE-ID: CWE-862
Exploitation vector: Adjecent network
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a highly privileged adjacent-network attacker to mirror HTTP traffic to any Service in any namespace in a Cilium cluster.
The vulnerability exists due to missing ReferenceGrant authorization checks for cross-namespace HTTPRoute traffic mirroring when Cilium's Gateway API functionality, which is disabled by default, is enabled. A highly privileged adjacent-network attacker can create or update namespaced HTTPRoutes with the required permissions to send mirrored traffic across namespace boundaries without authorization.
Affected software
Cilium
How to mitigate CVE-2026-56742
Install security update from vendor's website.
Cilium - addressed in versions 1.17.17, 1.18.11, 1.19.5