UEFI Firmware Parser has a stack out-of-bounds write in tiano decompressor MakeTable
uefi-firmware contains a stack out-of-bounds write vulnerability in the native tiano/EFI decompressor. in uefi_firmware/compression/Tiano/Decompress.c, MakeTable() does not validate that bit-length values read from the compressed bitstream are within the expected range (0..16). a crafted firmware blob can supply bit lengths greater than 16, causing out-of-bounds writes to the stack-allocated Count[17] array and related decode tables.
reachability is through the normal parsing path: CompressedSection.process() -> efi_compressor.TianoDecompress() -> TianoDecompress() -> ReadPTLen() -> MakeTable().
Minimum impact is a deterministic crash; depending on build/runtime details, the stack memory corruption may be exploitable for code execution in the context of the parsing process. this project shipped its own copy of the decompressor without the upstream EDK2 hardening for this bug class.
References:
- PR: https://github.com/theopolis/uefi-firmware-parser/pull/145
- fix commit: https://github.com/theopolis/uefi-firmware-parser/commit/bf3dfaa8a05675bae6ea0cbfa082ddcebfcde23e
- upstream related fixes: CVE-2017-5731, CVE-2017-5732, CVE-2017-5733, CVE-2017-5734, CVE-2017-5735
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | uefi-firmware | <= 1.12 | no fix |
References
- https://github.com/theopolis/uefi-firmware-parser/security/advisories/GHSA-2689-5p89-6j3j
- https://github.com/theopolis/uefi-firmware-parser/pull/145
- https://github.com/theopolis/uefi-firmware-parser/commit/bf3dfaa8a05675bae6ea0cbfa082ddcebfcde23e
- https://github.com/theopolis/uefi-firmware-parser
- https://pypi.org/project/uefi-firmware
- https://github.com/advisories/GHSA-2689-5p89-6j3j
- https://nvd.nist.gov/vuln/detail/CVE-2026-54333
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H- Weakness (CWE)
CWE-787- Platform
- Python (PyPI)
- Package
uefi-firmware- Disclosed
- 16.04.2026
- Updated
- 11.10.2026 14:17
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2026-3393 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-2689-5p89-6j3j - CC BY 4.0
Vulnerability history: uefi-firmware
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 2
- First → latest
- 04.2026 04.2026
- Without a fix
- 2
- Exploited in attacks
- 0
Severity breakdown
- Critical 2
Disclosures per year
- 2026: 2
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UEFI Firmware Parser has a stack out-of-bounds write in tiano decompressor MakeTable this entry
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