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VulnerabilityPublished Updated

CVE-2026-54334: theopolis uefi-firmware-parser · Out-of-bounds Write

Affects theopolis uefi-firmware-parserSource CVE Database V5

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Not known to be exploited · CVSS 9.8 Critical : upgrade to 1.14 as a priority.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.8% chance of exploitation in 30 days – higher than 56% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.14
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade uefi-firmware-parser and theopolis/uefi-firmware-parser to 1.14.

Affected software

ProductAffectedFixed in
theopolisuefi-firmware-parserAffected
  • <1.14
Fixed in
  • 1.14
GitHubtheopolis/uefi-firmware-parserpkg:github/theopolis/uefi-firmware-parserOther threatsAffected
  • <1.14
Fixed in
  • 1.14

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade to version 1.14 or later of theopolis uefi-firmware-parser where this vulnerability is fixed. No other mitigations are indicated by the vendor advisory.

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.

References

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