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High, CVSS 8.9

Go-Attestation: Hash injection into trusted measurement list via unskipped SignatureHeaderSize vendor bytes in parseEfiSignatureList()

CVE-2026-12681GHSA-9r4w-jg96-92mv

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (github.com/google/go-attestation 0.6.1), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
8.9 · CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X · score source
EPSS
  • CVE-2026-12681: 0.27% estimated exploitation activity in the next 30 days; percentile 19.07 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary parseEfiSignatureList() in attest/internal/events.go does not skip SignatureHeaderSize vendor bytes before reading EFISIGNATURELIST 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:…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 1 · created ·

    Published from ghsa record GHSA-9r4w-jg96-92mv

Agent brief

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# Patch Next advisory brief: CVE-2026-12681

Advisory: Go-Attestation: Hash injection into trusted measurement list via unskipped SignatureHeaderSize vendor bytes in parseEfiSignatureList()
IDs: CVE-2026-12681, GHSA-9r4w-jg96-92mv
Record: https://patchnext.com/advisories/cve-2026-12681 (revision 1, source checked 26 Oct 2026, 15:28 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.9)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/google/go-attestation 0.6.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/google/go-attestation: affected <= 0.6.0; fixed in 0.6.1

## Suggested inspection (read-only)
- Go github.com/google/go-attestation: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/google/go-attestation.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-9r4w-jg96-92mv (GitHub-reviewed advisory GHSA-9r4w-jg96-92mv lists affected ranges: Go github.com/google/go-attestation >=0 <=0.6.0)

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