CVE-2023-30851 — cilium
LOWCVE-2023-30851 is a low-severity (CVSS 2.6) CWE-693 vulnerability in github.com/cilium/cilium. A fix is available for github.com/cilium/cilium — see the affected versions and patch details below.
Potential HTTP policy bypass when using header rules in Cilium
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 CVE-2023-30851.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2023-30851 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,567 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/cilium/cilium🐹github.com/cilium/cilium🐹github.com/cilium/ciliumReal-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
This issue only impacts users who:
- Have a HTTP policy that applies to multiple
toEndpointsAND - Have an allow-all rule in place that affects only one of those endpoints
In such cases, a wildcard rule will be appended to the set of HTTP rules, which could cause bypass of HTTP policies.
Patches
This issue has been patched in Cilium 1.11.16, 1.12.9, and 1.13.2.
Workarounds
Rewrite HTTP rules for each endpoint separately. For example, if the initial rule looks like:
egress:
- toEndpoints:
- matchLabels:
k8s:kind: echo
- matchLabels:
k8s:kind: example
toPorts:
- ports:
- port: "8080"
protocol: TCP
rules:
http:
- method: "GET"
It should be rewritten to:
egress:
- toEndpoints:
- matchLabels:
k8s:kind: echo
toPorts:
- ports:
- port: "8080"
protocol: TCP
rules:
http:
- method: "GET"
- toEndpoints:
- matchLabels:
k8s:kind: example
toPorts:
- ports:
- port: "8080"
protocol: TCP
rules:
http:
- method: "GET"
Acknowledgements
The Cilium community has worked together with members of Isovalent to prepare these mitigations. Special thanks to @jrajahalme for investigating and fixing the issue.
For more information
If you have any questions or comments about this advisory, please reach out on Slack.
As usual, if you think you found a related vulnerability, we strongly encourage you to report security vulnerabilities to our private security mailing list: [email protected] - first, before disclosing them in any public forums. This is a private mailing list where only members of the Cilium internal security team are subscribed to, and is treated as top priority.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/cilium/cilium | all versions | 1.11.16go get github.com/cilium/cilium@v1.11.16 |
| 🐹Go | github.com/cilium/cilium | ≥ 1.12.0&&< 1.12.9 | 1.12.9go get github.com/cilium/cilium@v1.12.9 |
| 🐹Go | github.com/cilium/cilium | ≥ 1.13.0&&< 1.13.2 | 1.13.2go get github.com/cilium/cilium@v1.13.2 |
Detection & mitigation playbook
Open-source dependencyDetect
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.
Fix
Update github.com/cilium/cilium to 1.11.16 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-30851 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2023-30851 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-30851. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-30851 in your dependencies?
O3 Security finds CVE-2023-30851 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.