Summary
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.
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.
The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.
CVE-2025-23028 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (1.14.18, 1.15.12, 1.16.5); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
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
Frequently Asked Questions
- What is CVE-2025-23028? CVE-2025-23028 is a medium-severity allocation of resources without limits or throttling vulnerability in github.com/cilium/cilium (go), affecting versions >= 1.14.0, < 1.14.18. It is fixed in 1.14.18, 1.15.12, 1.16.5. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
- How severe is CVE-2025-23028? CVE-2025-23028 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of github.com/cilium/cilium are affected by CVE-2025-23028? github.com/cilium/cilium (go) versions >= 1.14.0, < 1.14.18 is affected.
- Is there a fix for CVE-2025-23028? Yes. CVE-2025-23028 is fixed in 1.14.18, 1.15.12, 1.16.5. Upgrade to this version or later.
- Is CVE-2025-23028 exploitable, and should I be worried? Whether CVE-2025-23028 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-23028 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2025-23028?
- Upgrade
github.com/cilium/ciliumto 1.14.18 or later - Upgrade
github.com/cilium/ciliumto 1.15.12 or later - Upgrade
github.com/cilium/ciliumto 1.16.5 or later
- Upgrade