GHSA-hm2w-vr2p-hq7w

Source

https://github.com/advisories/GHSA-hm2w-vr2p-hq7w

Import Source

https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-hm2w-vr2p-hq7w/GHSA-hm2w-vr2p-hq7w.json

JSON Data

https://api.osv.dev/v1/vulns/GHSA-hm2w-vr2p-hq7w

Published

2026-04-16T01:31:09Z

Modified

2026-04-16T01:49:38.077556Z

Severity

9.8 (Critical) CVSS_V3 - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H CVSS Calculator

Summary

UEFI Firmware Parser has a heap out-of-bounds write in tiano decompressor ReadCLen

Details

uefi-firmware contains a heap out-of-bounds write vulnerability in the native tiano/EFI decompressor. in uefi_firmware/compression/Tiano/Decompress.c, ReadCLen() reads Number = GetBits(Sd, CBIT) with CBIT = 9, so Number can be as large as 511, while the destination array Sd->mCLen has NC = 510 elements. the loop writes while Index < Number without enforcing Index < NC. additionally, the CharC == 2 run-length path performs GetBits(Sd, 9) + 20, allowing up to 531 zero writes through Sd->mCLen[Index++] = 0.

Reachability is through the normal parsing path: CompressedSection.process() -> efi_compressor.TianoDecompress() -> TianoDecompress() -> DecodeC() -> ReadCLen().

Minimum impact is a deterministic crash; depending on build/runtime details, the heap 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.

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

Database specific

{
    "github_reviewed_at": "2026-04-16T01:31:09Z",
    "nvd_published_at": null,
    "cwe_ids": [
        "CWE-787"
    ],
    "severity": "CRITICAL",
    "github_reviewed": true
}

References

Affected packages

PyPI / uefi-firmware

Package

Name: uefi-firmware; View open source insights on deps.dev
Purl: pkg:pypi/uefi-firmware

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0Unknown introduced version / All previous versions are affected

Last affected

1.12

Affected versions

1.*

1.1

1.2

1.3

1.4

1.6

1.7

1.8

1.9

1.10

1.11

Database specific

source

"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/04/GHSA-hm2w-vr2p-hq7w/GHSA-hm2w-vr2p-hq7w.json"