CVE-2026-54333: UEFI Firmware Parser has a stack out-of-bounds write in tiano decompressor MakeTable
uefi-firmware contains a stack out-of-bounds write vulnerability in the native tiano/EFI decompressor. in uefifirmware/compression/Tiano/Decompress.c, MakeTable() does not validate that bit-length values read from the compressed bitstream are within the expected range (0..16).
Published Apr 16, 2026 · Updated Jul 8, 2026
Affected packages
uefi-firmware
- Ecosystem
- PyPI
- Affected
- <= 1.12
- Fixed in
- No patched version yet
- Check
pip show uefi-firmware
Advisory details
From the GitHub Advisory Database (CC BY 4.0).
uefi-firmware contains a stack out-of-bounds write vulnerability in the native tiano/EFI decompressor. in uefi_firmware/compression/Tiano/Decompress.c, MakeTable() does not validate that bit-length values read from the compressed bitstream are within the expected range (0..16). a crafted firmware blob can supply bit lengths greater than 16, causing out-of-bounds writes to the stack-allocated Count[17] array and related decode tables.
reachability is through the normal parsing path: CompressedSection.process() -> efi_compressor.TianoDecompress() -> TianoDecompress() -> ReadPTLen() -> MakeTable().
Minimum impact is a deterministic crash; depending on build/runtime details, the stack memory corruption may be exploitable for code execution in the context of the parsing process. this project shipped its own copy of the decompressor without the upstream EDK2 hardening for this bug class.
References:
- PR:
- fix commit:
- upstream related fixes: CVE-2017-5731, CVE-2017-5732, CVE-2017-5733, CVE-2017-5734, CVE-2017-5735
Credited to 1seal.
References
How this page is made: the data panel comes from the GitHub Advisory Database, CISA’s KEV catalog, the NVD and FIRST EPSS, and updates twice a day. No analysis has been written for this entry yet. Methodology