CVE-2026-31961

Fixed in Quill v0.7.1

Workarounds

None

Credit

Anchore would like to thank opera-aklajn (Opera) for reporting this vulnerability

Resources

• Inside code signing: hashes (Apple documentation)

Quill before version v0.7.1 contains an unbounded memory allocation vulnerability when parsing Mach-O binaries. Exploitation requires that Quill processes an attacker-supplied Mach-O binary, which is most likely in environments such as CI/CD pipelines, shared signing services, or any workflow where externally-submitted binaries are accepted for signing.

When parsing a Mach-O binary, Quill reads several size and count fields from the LC_CODE_SIGNATURE load command and embedded code signing structures (SuperBlob, BlobIndex) and uses them to allocate memory buffers without validating that the values are reasonable or consistent with the actual file size. Affected fields include DataSize, DataOffset, and Size from the load command, Count from the SuperBlob header, and Length from individual blob headers. An attacker can craft a minimal (~4KB) malicious Mach-O binary with extremely large values in these fields, causing Quill to attempt to allocate excessive memory. This leads to memory exhaustion and denial of service, potentially crashing the host process. Both the Quill CLI and Go library are affected when used to parse untrusted Mach-O files.

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-2026-31961 has a CVSS score of 5.5 (Medium). The vector is requires local access, low 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 (0.7.1); upgrading removes the vulnerable code path.

Kodem intelligence

1. What is CVE-2026-31961? CVE-2026-31961 is a medium-severity allocation of resources without limits or throttling vulnerability in github.com/anchore/quill (go), affecting versions < 0.7.1. It is fixed in 0.7.1. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
2. How severe is CVE-2026-31961? CVE-2026-31961 has a CVSS score of 5.5 (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.
3. Which versions of github.com/anchore/quill are affected by CVE-2026-31961? github.com/anchore/quill (go) versions < 0.7.1 is affected.
4. Is there a fix for CVE-2026-31961? Yes. CVE-2026-31961 is fixed in 0.7.1. Upgrade to this version or later.
5. Is CVE-2026-31961 exploitable, and should I be worried? Whether CVE-2026-31961 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
6. What actually determines whether CVE-2026-31961 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.
7. How do I fix CVE-2026-31961? Upgrade github.com/anchore/quill to 0.7.1 or later.