GHSA-9m5p-c77c-f9j7
MEDIUMDoS in Cilium agent DNS proxy from crafted DNS responses
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.
Blast Radius
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
In a Kubernetes cluster where Cilium is configured to proxy DNS traffic, an attacker can crash Cilium agents by sending a crafted DNS response to workloads from outside the cluster.
For traffic that is allowed but without using DNS-based policy, the dataplane will continue to pass traffic as configured at the time of the DoS. For workloads that have DNS-based policy configured, existing connections may continue to operate, and new connections made without relying on DNS resolution may continue to be established, but new connections which rely on DNS resolution may be disrupted. Any configuration changes that affect the impacted agent may not be applied until the agent is able to restart.
Patches
This issue affects:
- Cilium v1.14 between v1.14.0 and v1.14.17 inclusive
- Cilium v1.15 between v1.15.0 and v1.15.11 inclusive
- Cilium v1.16 between v1.16.0 and v1.16.4 inclusive
This issue is fixed in:
- Cilium v1.14.18
- Cilium v1.15.12
- Cilium v1.16.5
Workarounds
There are no known workarounds to this issue.
Acknowledgements
The Cilium community has worked together with members of Isovalent and the Cisco Advanced Security Initiatives Group (ASIG) to prepare these mitigations. Special thanks to @kokelley-cisco for reporting this issue and @bimmlerd 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
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/cilium/cilium | ≥ 1.14.0&&< 1.14.18 | 1.14.18 |
| 🐹Go | github.com/cilium/cilium | ≥ 1.15.0&&< 1.15.12 | 1.15.12 |
| 🐹Go | github.com/cilium/cilium | ≥ 1.16.0&&< 1.16.5 | 1.16.5 |
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. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/cilium/cilium to 1.14.18 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-9m5p-c77c-f9j7 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 pinpoints whether GHSA-9m5p-c77c-f9j7 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-9m5p-c77c-f9j7. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-9m5p-c77c-f9j7 in your dependencies?
O3 detects GHSA-9m5p-c77c-f9j7 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.