GHSA-9R4W-JG96-92MV

parseEfiSignatureList() in attest/internal/events.go does not skip SignatureHeaderSize vendor bytes before reading EFI_SIGNATURE_LIST signature entries, violating UEFI specification section 31.4.1.

Root Cause

After binary.Read(&signatures.Header) reads 28 bytes, buf points to the start of the SignatureHeaderSize vendor bytes. Both entry loops start at sigOffset := 0 instead of sigOffset := SignatureHeaderSize, causing vendor bytes to be read as signature entries.

Affected versions

All versions through commit f877374 (2026-05-15).

For hashSHA256SigGUID lists, attacker-controlled vendor header bytes are appended directly to the trusted SHA256 hash list. A crafted TPM event log can inject arbitrary SHA256 hashes into the verifier's trusted measurement database, allowing a remote attestation verifier to accept a compromised boot state as legitimate, breaking the core integrity guarantee of remote attestation.

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

GHSA-9R4W-JG96-92MV has a CVSS score of 6.8 (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. No fixed version is listed yet, so configuration controls and monitoring matter more in the interim.

Kodem intelligence

Pull request: https://github.com/google/go-attestation/pull/502

• Add bound check: SignatureHeaderSize must not exceed remaining list space
• Skip SignatureHeaderSize bytes before both entry loops
• Regression test: TestParseEfiSignatureListNonZeroSignatureHeaderSize

1. What is GHSA-9R4W-JG96-92MV? GHSA-9R4W-JG96-92MV is a medium-severity improper input validation vulnerability in github.com/google/go-attestation (go), affecting versions <= 0.5.0. No fixed version is listed yet. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is GHSA-9R4W-JG96-92MV? GHSA-9R4W-JG96-92MV has a CVSS score of 6.8 (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/google/go-attestation are affected by GHSA-9R4W-JG96-92MV? github.com/google/go-attestation (go) versions <= 0.5.0 is affected.
4. Is there a fix for GHSA-9R4W-JG96-92MV? No fixed version is listed for GHSA-9R4W-JG96-92MV yet. Monitor the advisory for updates and apply mitigations in the interim.
5. Is GHSA-9R4W-JG96-92MV exploitable, and should I be worried? Whether GHSA-9R4W-JG96-92MV 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 GHSA-9R4W-JG96-92MV 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 GHSA-9R4W-JG96-92MV? No fixed version is listed yet. In the interim: Validate all external input against an allowlist of expected values, types, and ranges before processing.