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MEDIUM severity

Cilium has an information leakage via insecure default Hubble UI CORS headerGHSA-h78m-j95m-5356

MEDIUMFix: cilium/cilium@a3489f1

GHSA-h78m-j95m-5356 is a medium-severity (CVSS 6.5) Information Exposure vulnerability in github.com/cilium/cilium. A fix is available for github.com/cilium/cilium — see the affected versions and patch details below.

Also known asBIT-cilium-2025-23047BIT-cilium-operator-2025-23047BIT-hubble-relay-2025-23047CVE-2025-23047GO-2025-3416
Published
Updated
Affected
3 pkgs
Patched
3 / 3
Exploits
None indexed
Exploitation data as of Oct 31, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-h78m-j95m-5356.

EPSS Exploitation Probability

via FIRST.org ↗
0.5%probability of exploitation in next 30 days
Lower Risk-0.01%
Lower risk than most CVEs42th percentile — riskier than 42% of all scored CVEsHighest risk
0.00%0.33%0.67%1.00%0.1%0.5%May 26Aug 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

3 pkgs affected
🐹github.com/cilium/cilium🐹github.com/cilium/cilium🐹github.com/cilium/cilium

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

Impact

For users who deploy Hubble UI using either Cilium CLI or via the Cilium Helm chart, an insecure default Access-Control-Allow-Origin header value could lead to sensitive data exposure. A user with access to a Hubble UI instance affected by this issue could leak configuration details about the Kubernetes cluster which Hubble UI is monitoring, including node names, IP addresses, and other metadata about workloads and the cluster networking configuration. In order for this vulnerability to be exploited, a victim would have to first visit a malicious page.

Patches

This issue was patched in https://github.com/cilium/cilium/commit/a3489f190ba6e87b5336ee685fb6c80b1270d06d

This issue affects:

  • Cilium between v1.14.0 and v1.14.18 inclusive
  • Cilium between v1.15.0 and v1.15.12 inclusive
  • Cilium between v1.16.0 and v1.16.5 inclusive

This issue is patched in:

  • Cilium v1.14.19
  • Cilium v1.15.13
  • Cilium v1.16.6

Workarounds

Users who deploy Hubble UI using the Cilium Helm chart directly can remove the CORS headers from the Helm template as shown in the patch.

Acknowledgements

The Cilium community has worked together with members of Isovalent to prepare these mitigations. Special thanks to @ciffelia for reporting this issue and to @geakstr for the fix.

For more information

If you have any questions or comments about this advisory, please reach out on Slack.

If you think you have found a vulnerability affecting Cilium, we strongly encourage you to report it to our security mailing list at [email protected]. This is a private mailing list for the Cilium security team, and your report will be treated as top priority.

Affected Packages

3 total 3 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/cilium/cilium≥ 1.14.0&&< 1.14.191.14.19go get github.com/cilium/cilium@v1.14.19
🐹Gogithub.com/cilium/cilium≥ 1.15.0&&< 1.15.131.15.13go get github.com/cilium/cilium@v1.15.13
🐹Gogithub.com/cilium/cilium≥ 1.16.0&&< 1.16.61.16.6go get github.com/cilium/cilium@v1.16.6

Affected Products

1 product · 3 configurations
Application
ciliumcilium
≥ 1.16.0 && < 1.16.6
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/cilium/cilium, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/cilium/cilium to 1.14.19 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-h78m-j95m-5356 is resolved across your whole dependency graph.

  3. Workarounds

    Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.

Frequently Asked Questions

### Impact For users who deploy Hubble UI using either Cilium CLI or via the Cilium Helm chart, an insecure default `Access-Control-Allow-Origin` header value could lead to sensitive data exposure. A user with access to a Hubble UI instance affected by this issue could leak configuration details about the Kubernetes cluster which Hubble UI is monitoring, including node names, IP addresses, and other metadata about workloads and the cluster networking configuration. In order for this vulnerability to be exploited, a victim would have to first visit a malicious page. ### Patches This issue wa
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Cilium has an information leakage via insecure default…