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CiliumApplication

CVE-2026-56742

HIGH · 8.9 CVSS v3.1 Published 2026-07-15
Fix available
A fix is available. Upgrade to 1.17.17 / 1.18.11 or later.
See remediation →
91/100
Remediation priority · Urgent
Zero-click 5 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

In Cilium clusters with Gateway API enabled, users having permissions to create or update namespaced HTTPRoutes can bypass ReferenceGrant authorization to mirror HTTP traffic to any Service in any namespace, not just permitted ones.

MitigationUpgrade Cilium to version 1.17.17, 1.18.11, or 1.19.5. If Gateway API is not needed, ensure it remains disabled.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
CiliumApplication
Affected:< 1.17.17>= 1.18.0, < 1.18.11>= 1.19.0, < 1.19.5

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Adjacent
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
Low

CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the installed Cilium version
    Run `cilium version` or `kubectl get cilium -o jsonpath='{.items[0].status.version}'` in the cluster, or check the Cilium agent pod image tag
    Affected if The version is less than 1.17.17, between 1.18.0 and 1.18.11 (exclusive), or between 1.19.0 and 1.19.5 (exclusive)
  2. Determine if Gateway API is enabled
    Check the Cilium configuration: run `cilium config view | grep gateway-api` or inspect the Cilium Operator/Agent config map for `enable-gateway-api` set to true
    Affected if Gateway API is explicitly enabled (value is true), as the vulnerability only applies when this feature is active
  3. Check for existing HTTPRoute resources
    Run `kubectl get httproutes -A -o wide` to list all HTTPRoute resources in the cluster
    Affected if HTTPRoutes exist that reference backendRefs pointing to Services in namespaces other than the HTTPRoute's namespace, especially without corresponding ReferenceGrant objects
  4. Verify ReferenceGrant coverage for cross-namespace references
    For each HTTPRoute with cross-namespace backendRefs, check if a ReferenceGrant exists in the target namespace: `kubectl get referencegrants -n <target-namespace>` and confirm it grants access from the HTTPRoute's namespace
    Affected if HTTPRoutes reference Services in other namespaces without a valid ReferenceGrant permitting that access, indicating potential exploitation of this bypass

The environment is affected if Gateway API is enabled AND the Cilium version falls within the affected ranges AND cross-namespace HTTPRoute backendRefs exist without proper ReferenceGrant authorization.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.17.17 / 1.18.11 / 1.19.5 or later
Fixed in 1.17.171.18.111.19.5
Interim mitigation

Upgrade Cilium to version 1.17.17, 1.18.11, or 1.19.5. If Gateway API is not needed, ensure it remains disabled.

Recommended fix High confidence

1.17.17, 1.18.11, or 1.19.5 (choose based on current major.minor branch)

  1. 1. Identify current Cilium version: kubectl get pod -n kube-system -l k8s-app=cilium -o jsonpath='{.items[0].spec.containers[0].image}'
  2. 2. Determine target version based on your current major.minor: if using 1.17.x upgrade to 1.17.17; if using 1.18.x upgrade to 1.18.11; if using 1.19.x upgrade to 1.19.5
  3. 3. Review the Cilium upgrade guide at docs.cilium.io/en/stable/operations/upgrade/ for your upgrade path
  4. 4. Backup current Cilium configuration: helm get values cilium -n kube-system > cilium-values-backup.yaml
  5. 5. Perform upgrade using Helm: helm upgrade cilium cilium/cilium --version <target-version> -n kube-system -f cilium-values-backup.yaml
  6. 6. Verify Gateway API CRDs are properly configured post-upgrade
  7. 7. Confirm the upgrade: kubectl get pod -n kube-system -l k8s-app=cilium and verify all pods are running
Caveat Check release notes for breaking changes between your current version and target version before upgrading

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Cilium Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-56742 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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