{"cve":"CVE-2026-54334","nvd":{"published":"2026-09-14T20:16:46.143","modified":"2026-09-30T17:51:56.193","status":"Deferred","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":["CWE-787"],"references":["https://github.com/theopolis/uefi-firmware-parser/commit/bf3dfaa8a05675bae6ea0cbfa082ddcebfcde23e","https://github.com/theopolis/uefi-firmware-parser/pull/145","https://github.com/theopolis/uefi-firmware-parser/releases/tag/v1.14","https://github.com/theopolis/uefi-firmware-parser/security/advisories/GHSA-hm2w-vr2p-hq7w"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:53:43.293028046+00:00"},"epss":{"cve":"CVE-2026-54334","score":0.00801,"percentile":0.56358,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-hm2w-vr2p-hq7w","url":"https://osv.dev/vulnerability/GHSA-hm2w-vr2p-hq7w","summary":"UEFI Firmware Parser has a heap out-of-bounds write in tiano decompressor ReadCLen","modified":"2026-07-13T16:43:42.463561576Z","packages":[{"ecosystem":"PyPI","name":"uefi-firmware","purl":"pkg:pypi/uefi-firmware","ranges":["<=1.12"],"fixed":[]}]},{"id":"PYSEC-2026-3394","url":"https://osv.dev/vulnerability/PYSEC-2026-3394","summary":"UEFI Firmware Parser has a heap out-of-bounds write in tiano decompressor ReadCLen","modified":"2026-07-13T16:33:27.543929183Z","packages":[{"ecosystem":"PyPI","name":"uefi-firmware","purl":"pkg:pypi/uefi-firmware","ranges":["<=1.12"],"fixed":[]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}