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Vulnerability · Published Feb 19, 2026 · Assigned by GitHub_M

CVE-2026-26963Cilium may not enforce host firewall policies when Native Routing, WireGuard and Node Encryption are enabled

Medium 6.1

In plain English

A medium-severity incorrect authorization in cilium from cilium. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.1% (higher than 3% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)6.1Medium
Exploit odds (30 days)0.1%top 96.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

Cilium is a networking, observability, and security solution with an eBPF-based dataplane. Versions 1.18.0 through 1.18.5 will incorrectly permit traffic from Pods on other nodes when Native Routing, WireGuard and Node Encryption are enabled. This issue has been fixed in version 1.18.6.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
Gogithub.com/cilium/cilium1.18.6GHSA-5r23-prx4-mqg3
Gogithub.com/cilium/cilium1.18.6GO-2026-4522
Ubuntu:22.04:LTSgolang-github-cilium-ebpfno fix listedUBUNTU-CVE-2026-26963
Ubuntu:24.04:LTSgolang-github-cilium-ebpfno fix listedUBUNTU-CVE-2026-26963
Ubuntu:25.10golang-github-cilium-ebpfno fix listedUBUNTU-CVE-2026-26963
Ubuntu:26.04:LTSgolang-github-cilium-ebpfno fix listedUBUNTU-CVE-2026-26963
Ubuntu:26.10golang-github-cilium-ebpfno fix listedUBUNTU-CVE-2026-26963

Affected products (as reported)

VendorProductVersions
cilium cilium >= 1.18.0, < 1.18.6

Weakness: CWE-863 · Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N

References