GHSA-9r4w-jg96-92mv Go-Attestation: Hash injection into trusted measurement list via unskipped SignatureHeaderSize vendor bytes in parseEfiSignatureList()

• Go github.com/google/go-attestation: < 0.6.1 → fixed in 0.6.1

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`