Critical severity · published Sep 14, 2026
CVE-2026-54333
UEFI Firmware Parser: Stack out-of-bounds write in tiano decompressor MakeTable
9.8
CVSS
0.8%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.8% · higher than 56% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
UE
uefi-firmware-parser · theopolis
< 1.14 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-54333
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-54333
github.com
https://github.com/theopolis/uefi-firmware-parser/commit/bf3dfaa8a05675bae6ea0cbfa082ddcebfcde23e
github.com
https://github.com/theopolis/uefi-firmware-parser/pull/145
github.com
https://github.com/theopolis/uefi-firmware-parser/releases/tag/v1.14
github.com
https://github.com/theopolis/uefi-firmware-parser/security/advisories/GHSA-2689-5p89-6j3j
More from uefi-firmware-parser
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