Vulnerability Description
UEFI Firmware Parser parses BIOS, Intel ME, and UEFI firmware structures including volumes, file systems, and files. Prior to 1.14, ReadCLen() in uefi_firmware/compression/Tiano/Decompress.c reads Number from GetBits(Sd, CBIT) with CBIT = 9 and can obtain 511 entries for the 510-element Sd->mCLen heap array because its loop does not enforce Index < NC. The CharC == 2 run-length path can additionally request up to 531 zero writes through Sd->mCLen[Index++] = 0. The normal CompressedSection.process() to efi_compressor.TianoDecompress() to TianoDecompress() to DecodeC() to ReadCLen() parsing path therefore permits crafted Tiano or EFI compressed firmware to corrupt heap memory, deterministically crash the parsing process, and potentially execute code depending on build and runtime details. This issue is fixed in version 1.14.
CVSS Score
CRITICAL
Related Weaknesses (CWE)
References
- https://github.com/theopolis/uefi-firmware-parser/commit/bf3dfaa8a05675bae6ea0cb
- https://github.com/theopolis/uefi-firmware-parser/pull/145
- https://github.com/theopolis/uefi-firmware-parser/releases/tag/v1.14
- https://github.com/theopolis/uefi-firmware-parser/security/advisories/GHSA-hm2w-
FAQ
What is CVE-2026-54334?
CVE-2026-54334 is a vulnerability with a CVSS score of 9.8 (CRITICAL). UEFI Firmware Parser parses BIOS, Intel ME, and UEFI firmware structures including volumes, file systems, and files. Prior to 1.14, ReadCLen() in uefi_firmware/compression/Tiano/Decompress.c reads Num...
How severe is CVE-2026-54334?
CVE-2026-54334 has been rated CRITICAL with a CVSS base score of 9.8/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-54334?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.