---
id: CVE-2026-54333
title: >-
  UEFI Firmware Parser parses BIOS, Intel ME, and UEFI firmware structures
  including volumes, file systems, and files
summary: >-
  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…
severity: critical
cvss: 9.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-787
vendor: theopolis
product: uefi-firmware-parser
affected:
  - uefi-firmware-parser < 1.14
published: '2026-09-14'
updated: '2026-09-15'
sourceUpdated: '2026-09-15T14:16:59.540'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-54333'
references:
  - url: >-
      https://github.com/theopolis/uefi-firmware-parser/commit/bf3dfaa8a05675bae6ea0cbfa082ddcebfcde23e
    label: security-advisories@github.com
  - url: 'https://github.com/theopolis/uefi-firmware-parser/pull/145'
    label: security-advisories@github.com
  - url: 'https://github.com/theopolis/uefi-firmware-parser/releases/tag/v1.14'
    label: security-advisories@github.com
  - url: >-
      https://github.com/theopolis/uefi-firmware-parser/security/advisories/GHSA-2689-5p89-6j3j
    label: security-advisories@github.com
  - url: 'https://github.com/theopolis/uefi-firmware-parser'
tags:
  - nvd
  - cve.org
  - osv
  - pip
ssvc:
  exploitation: none
  automatable: 'yes'
  technicalImpact: total
  timestamp: '2026-09-15T13:30:40.310782Z'
epss: 0.00801
epssPercentile: 0.54777
aliases:
  - GHSA-2689-5p89-6j3j
ecosystem: pip
ingestedAt: '2026-07-08T18:25:44.151Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-54333)

Affected packages:

- `uefi-firmware <= 1.12`

Source: https://osv.dev/vulnerability/GHSA-2689-5p89-6j3j