Review reviewHigh

CVE-2026-56742

cilium

Cilium is a networking, observability, and security solution. Prior to 1.17.17, 1.18.11, and 1.19.5, Cilium clusters using Gateway API allow users with permissions to create or update namespaced HTTPRoutes to mirror HTTP traffic to any Service in any namespace, bypassing the ReferenceGrant authorization mechanism. Gateway API functionality is disabled by default. This issue is fixed in versions 1.17.17, 1.18.11, and 1.19.5.

CVSS: 8.9
EPSS: 0.17%
CISA KEV: Not listed
Published: 2026.07.16

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.17%

Technical severityCVSS 8.9

Vulnerability overview

Affected product and versions

Product: cilium
Affected versions: >= < 1.17.17, >= >= 1.18.0, < 1.18.11, >= >= 1.19.0, < 1.19.5, < 1.17.17, >= 1.18.0 < 1.18.11, >= 1.19.0 < 1.19.5
Fixed versions: 1.17.17, 1.18.11, 1.19.5

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that cilium and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L
CWE: CWE-862