Summary
notation-go has excessive memory allocation on verification
Workarounds
Users can review their own trust policy file and check if the identity string contains =#. Meanwhile, users should only put trusted certificates in their trust stores referenced by their own trust policy files, and make sure the authenticity validation is set to enforce
Credits
The notation-go project would like to thank Adam Korczynski (@AdamKorcz) for responsibly disclosing this issue during a security fuzzing audit sponsored by CNCF and Shiwei Zhang (@shizhMSFT) for root cause analysis and detailed vulnerability report.
References
Impact
notation-go users will find their application using excessive memory when verifying signatures and the application will be finally killed, and thus availability is impacted.
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-2023-25656 has a CVSS score of 7.5 (High). 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 (1.0.0-rc.3); 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.
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The problem has been patched in the release v1.0.0-rc.3. Users should upgrade their notation-go packages to v1.0.0-rc.3 or above.
Frequently Asked Questions
- What is CVE-2023-25656? CVE-2023-25656 is a high-severity allocation of resources without limits or throttling vulnerability in github.com/notaryproject/notation-go (go), affecting versions < 1.0.0-rc.3. It is fixed in 1.0.0-rc.3. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
- How severe is CVE-2023-25656? CVE-2023-25656 has a CVSS score of 7.5 (High). 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/notaryproject/notation-go are affected by CVE-2023-25656? github.com/notaryproject/notation-go (go) versions < 1.0.0-rc.3 is affected.
- Is there a fix for CVE-2023-25656? Yes. CVE-2023-25656 is fixed in 1.0.0-rc.3. Upgrade to this version or later.
- Is CVE-2023-25656 exploitable, and should I be worried? Whether CVE-2023-25656 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-2023-25656 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-2023-25656? Upgrade
github.com/notaryproject/notation-goto 1.0.0-rc.3 or later.