Skip to content

CiliumLocalRedirectPolicy addressMatcher allows cross-namespace service traffic hijacking and can break service translation

Moderate severity GitHub Reviewed Published Jun 16, 2026 in cilium/cilium • Updated Jul 6, 2026

Package

gomod github.com/cilium/cilium (Go)

Affected versions

>= 1.19.0, < 1.19.4
>= 1.18.2, < 1.18.10
< 1.17.16

Patched versions

1.19.4
1.18.10
1.17.16

Description

Impact

Users with the ability to create CiliumLocalRedirectPolicies can specify arbitrary ClusterIPs via addressMatcher, which enables hijacking traffic to Services in any namespace, bypassing the namespace-scoping guarantees enforced by serviceMatcher.

In addition, deleting such a policy can corrupt Cilium's internal service state, causing service translation to stop working entirely for the affected Service.

Patches

This issue affects:

  • Cilium v1.19.0 to v1.19.3 inclusive (fixed in PR #45584)
  • Cilium v1.18.2 to v1.18.9 inclusive (fixed in PR #45585)
  • All versions of Cilium prior to v1.17.16 (fixed in PR #45412)

This issue has been patched in:

  • Cilium v1.19.4
  • Cilium v1.18.10
  • Cilium v1.17.16

Workarounds

There is no workaround to this issue.

Acknowledgements

The Cilium community has worked together with members of Isovalent to prepare these mitigations. Special thanks to @ysksuzuki for investigating and fixing the issue.

For more information

If there are any questions or comments about this advisory, please reach out on Slack.

To report potential vulnerabilities affecting Cilium, it strongly is encouraged to report them through the security mailing list at security@cilium.io. This is a private mailing list for the Cilium security team, and reports will be treated as a top priority.

References

@ferozsalam ferozsalam published to cilium/cilium Jun 16, 2026
Published to the GitHub Advisory Database Jul 6, 2026
Reviewed Jul 6, 2026
Last updated Jul 6, 2026

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Adjacent
Attack complexity
Low
Privileges required
High
User interaction
None
Scope
Changed
Confidentiality
Low
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:A/AC:L/PR:H/UI:N/S:C/C:L/I:N/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(11th percentile)

Weaknesses

URL Redirection to Untrusted Site ('Open Redirect')

The web application accepts a user-controlled input that specifies a link to an external site, and uses that link in a redirect. Learn more on MITRE.

CVE ID

CVE-2026-53935

GHSA ID

GHSA-q6h5-q3q6-f87x

Source code

Loading Checking history
See something to contribute? Suggest improvements for this vulnerability.