---
id: CVE-2026-12681
aliases:
  - GHSA-9r4w-jg96-92mv
  - GO-2026-5298
title: >-
  Go-Attestation: Hash injection into trusted measurement list via unskipped
  SignatureHeaderSize vendor bytes in parseEfiSignatureList()
summary: >-
  Go-Attestation: Hash injection into trusted measurement list via unskipped
  SignatureHeaderSize vendor bytes in parseEfiSignatureList()
severity: medium
cvss: 6.8
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N'
vendor: google
product: github.com/google/go-attestation
ecosystem: go
affected:
  - github.com/google/go-attestation < 0.6.1
patched:
  - github.com/google/go-attestation 0.6.1
published: '2026-06-12'
updated: '2026-09-12'
sourceUpdated: '2026-09-12T05:15:04.693981733Z'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-9r4w-jg96-92mv'
references:
  - url: >-
      https://github.com/google/go-attestation/security/advisories/GHSA-9r4w-jg96-92mv
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-12681'
  - url: 'https://github.com/google/go-attestation/pull/502'
  - url: >-
      https://github.com/google/go-attestation/commit/b6e905e7ae52937f02b5ca494dd1c6a3ac7a1003
  - url: 'https://github.com/google/go-attestation'
  - url: 'https://github.com/google/go-attestation/releases/tag/v0.6.1'
  - url: 'https://github.com/google/go-attestation/releases/tag/v0.6.0'
tags:
  - osv
  - go
epss: 0.00268
epssPercentile: 0.1695
ingestedAt: '2026-07-09T18:56:36.289Z'
---

## Overview

## Summary

`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.

## Impact

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.

## 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).

## Fix

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`

## Affected packages

- `github.com/google/go-attestation < 0.6.1`

## Remediation

Upgrade to a patched release:

- `github.com/google/go-attestation 0.6.1`