CVE-2026-54333

CRITICAL 9.8

UEFI Firmware Parser: Stack out-of-bounds write in tiano decompressor MakeTable

CVSS Score

9.8

EPSS Score

0.0%

EPSS Percentile

0th

UEFI Firmware Parser parses BIOS, Intel ME, and UEFI firmware structures including volumes, file systems, and files. Prior to 1.14, MakeTable() in uefi_firmware/compression/Tiano/Decompress.c does not validate that bit-length values read from a crafted Tiano or EFI compressed firmware bitstream remain within the expected range from 0 through 16. The normal CompressedSection.process() to efi_compressor.TianoDecompress() to TianoDecompress() to ReadPTLen() to MakeTable() parsing path can consequently write beyond the stack-allocated Count[17] array and related decode tables. The resulting stack corruption deterministically crashes the parsing process and may permit code execution depending on build and runtime details. This issue is fixed in version 1.14.

CWE	CWE-787
Vendor	theopolis
Product	uefi-firmware-parser
Published	Sep 14, 2026
Last Updated	Sep 15, 2026

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CVSS v3 Breakdown

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Affected Versions

theopolis / uefi-firmware-parser

< 1.14

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/theopolis/uefi-firmware-parser/security/advisories/GHSA-2689-5p89-6j3j github.com: https://github.com/theopolis/uefi-firmware-parser/pull/145 github.com: https://github.com/theopolis/uefi-firmware-parser/commit/bf3dfaa8a05675bae6ea0cbfa082ddcebfcde23e github.com: https://github.com/theopolis/uefi-firmware-parser/releases/tag/v1.14