CVE-2026-56743
Cilium may unexpectedly allow ingress traffic from the local namespace when a Kubernetes NetworkPolicy is configured with an ipBlock match
Description
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.
INFO
Published Date :
July 15, 2026, 8:17 p.m.
Last Modified :
July 17, 2026, 5:29 p.m.
Remotely Exploit :
No
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update Cilium to version 1.19.5 or later.
- Review NetworkPolicy configurations for CIDR ipBlock rules.
- Verify correct traffic flow after update.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-56743.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-56743 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-56743
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-56743 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-56743 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
Initial Analysis by [email protected]
Jul. 17, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:cilium:cilium:*:*:*:*:*:*:*:* versions from (including) 1.19.0 up to (excluding) 1.19.5 Added Reference Type GitHub, Inc.: https://github.com/cilium/cilium/commit/1c84ae3b58a7cd54f7ee355e6c524c82f620eae8 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/cilium/cilium/commit/bacea640404c0805c23515353dc1681c5bf35171 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/cilium/cilium/pull/46305 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/cilium/cilium/pull/46456 Types: Patch Added Reference Type GitHub, Inc.: https://github.com/cilium/cilium/releases/tag/v1.19.5 Types: Release Notes Added Reference Type GitHub, Inc.: https://github.com/cilium/cilium/security/advisories/GHSA-fm8w-2m5w-9j7r Types: Vendor Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 16, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-56743', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-16T13:02:42.889041Z'} -
New CVE Received by [email protected]
Jul. 15, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'cilium', 'product': 'cilium', 'versions': [{'status': 'affected', 'version': '>= 1.19.0, < 1.19.5'}]}] Added Description 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. Added CVSS V3.1 AV:A/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N Added CWE CWE-863 Added Reference https://github.com/cilium/cilium/commit/1c84ae3b58a7cd54f7ee355e6c524c82f620eae8 Added Reference https://github.com/cilium/cilium/commit/bacea640404c0805c23515353dc1681c5bf35171 Added Reference https://github.com/cilium/cilium/pull/46305 Added Reference https://github.com/cilium/cilium/pull/46456 Added Reference https://github.com/cilium/cilium/releases/tag/v1.19.5 Added Reference https://github.com/cilium/cilium/security/advisories/GHSA-fm8w-2m5w-9j7r