Auth bypass in Cilium
CVE-2026-56743
Cilium is a networking, observability, and security solution. From 1.19.0 to 1.19.4, standard Kubernetes NetworkPolicy specifications using CIDR-based ipBlock rules without pod or namespace selectors erroneously generate a wildcard namespace allow rule when Cilium is configured with a custom clusterName rather than the default any value. The parser incorrectly instantiates a pod selector on selectorless peer definitions, allowing traffic from other workloads in the same namespace as the subject of the policy. This issue is fixed in version 1.19.5.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.002 (14.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 15th percentile — 14.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Cilium — versions >= 1.19.0, < 1.19.5
Weakness classification (CWE)
References
- github.com/cilium/cilium/security/advisories/GHSA-fm8w-2m5w-9j7r (Vendor Advisory)
- github.com/cilium/cilium/pull/46305 (Patch)
- github.com/cilium/cilium/pull/46456 (Patch)
- github.com/cilium/cilium/commit/1c84ae3b58a7cd54f7ee355e6c524c82f620eae8 (Patch)
- github.com/cilium/cilium/commit/bacea640404c0805c23515353dc1681c5bf35171 (Patch)
- github.com/cilium/cilium/releases/tag/v1.19.5 (Release Notes)
Frequently asked questions
- What is CVE-2026-56743?
- CVE-2026-56743 is a medium-severity vulnerability in Cilium, classified under Incorrect Authorization. CVSS score: 5.4/10. Published 2026-07-15.
- How severe is CVE-2026-56743?
- Medium severity. CVSS v3 base score is 5.4 out of 10.