CVE-2026-54333 json
UEFI Firmware Parser: Stack out-of-bounds write in tiano decompressor MakeTable
published 2026-04-16 6 mo ago modified 2026-09-30 39 d ago also GHSA-2689-5p89-6j3j , PYSEC-2026-3393 , EUVD-2026-78064
- cvss
- 9.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.8%
- EPSS 0.8% chance of exploitation in 30 days, percentile 56%
- public exploits
- 0
- none known
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 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.
Patch / fix
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- total
- Assessed
- 55 d ago
Exploit prediction
0.80% chance of exploitation in the next 30 days, higher than 56% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| GitHub | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| OSV | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | uefi-firmware | <=1.12 |
no fix listed |
Affected products
- theopolis uefi-firmware-parser
Classification
- Weakness
-
- CWE-787 Out-of-bounds Write
References
-
github.com
/theopolis/uefi-firmware-parser/pull/145
web
-
github.com
/theopolis/uefi-firmware-parser/commit/bf3dfaa8a05675bae6ea0cbfa082ddcebfcde23e
web
-
github.com
/theopolis/uefi-firmware-parser/security/advisories/GHSA-2689-5p89-6j3j
web
- github.com /theopolis/uefi-firmware-parser/releases/tag/v1.14
-
github.com
/theopolis/uefi-firmware-parser
package
-
pypi.org
/project/uefi-firmware
package
-
github.com
/advisories/GHSA-2689-5p89-6j3j
advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-54333
advisory
Sources
- CVE List CVE-2026-54333
- GitHub Advisory GHSA-2689-5p89-6j3j
- NVD CVE-2026-54333
- OSV PYSEC-2026-3393
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