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

## 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`

Source published

12 Jun 2026 15:04:43 UTC

Source modified

12 Sep 2026 05:15:04 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:H/A:N

CVSS_V4 · 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

Publisher rating · HIGH