CVE-2026-54334

CRITICALPre-NVD 9.89.8—
EchelonGraph scoreMEDIUM confidence

Score 9.8 from GitHub Security Advisory (severity: CRITICAL) published 2026-04-16. a secondary CVSS source baseline 9.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: ghsa, secondary
9.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: —CVSS: 9.8Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
9.8
EG Score
9.8(medium)
EG Risk
49(Track)
EG Risk 49/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity98% × 45%
Exploitation0% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
—
EPSS %ILE
—
KEV
Not listed

Published

April 16, 2026

Last Modified

September 14, 2026

Advisory Details (3)

Auto-updated Sep 14, 2026
Patch available. Sources: github_commit, github_pr, github.
github Patch Available

Heap out-of-bounds write in tiano decompressor `ReadCLen` · Advisory · theopolis/uefi-firmware-parser · GitHub

https://github.com/theopolis/uefi-firmware-parser/security/advisories/GHSA-hm2w-vr2p-hq7w
github_pr Patch Available

Apply hardening fixes from upstream Tiano implementation

Patch available: theopolis/uefi-firmware-parser v1.15 (PR #145 merged 2026-02-27)

https://github.com/theopolis/uefi-firmware-parser/pull/145
github_commit Patch Available

commit bf3dfaa8a056 (theopolis/uefi-firmware-parser)

Patch available: theopolis/uefi-firmware-parser v1.15 (contains commit bf3dfaa8a056)

https://github.com/theopolis/uefi-firmware-parser/commit/bf3dfaa8a05675bae6ea0cbfa082ddcebfcde23e

Vendor Advisories for CVE-2026-54334(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
pipuefi-firmware—ghsa

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
uefi-firmware1.1 ... 1.9 (10 versions)——

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 3× in last 7d / 4× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-09-14 20:27 UTCEG score recompute
  2. 2026-09-14 20:27 UTCGHSA enrichment
  3. 2026-09-14 20:16 UTCGHSA enrichment
  4. 2026-08-16 10:52 UTCGHSA enrichment
  5. 2026-08-16 06:37 UTCGHSA enrichment
  6. 2026-08-14 22:26 UTCGHSA enrichment
  7. 2026-08-14 18:12 UTCGHSA enrichment
  8. 2026-08-14 13:11 UTCGHSA enrichment
  9. 2026-08-14 08:57 UTCGHSA enrichment
  10. 2026-08-14 04:42 UTCGHSA enrichment
  11. 2026-08-13 08:55 UTCGHSA enrichment
  12. 2026-08-13 03:21 UTCGHSA enrichment
  13. 2026-08-12 23:07 UTCGHSA enrichment
  14. 2026-08-12 18:52 UTCGHSA enrichment
  15. 2026-08-12 01:32 UTCGHSA enrichment
  16. 2026-08-11 21:17 UTCGHSA enrichment
  17. 2026-08-11 17:03 UTCGHSA enrichment
  18. 2026-08-11 06:51 UTCGHSA enrichment
  19. 2026-08-11 02:37 UTCGHSA enrichment
  20. 2026-08-10 10:00 UTCGHSA enrichment
  21. 2026-08-10 05:45 UTCGHSA enrichment
  22. 2026-08-10 01:31 UTCGHSA enrichment
  23. 2026-08-09 21:15 UTCGHSA enrichment
  24. 2026-08-09 17:00 UTCGHSA enrichment
  25. 2026-08-09 12:46 UTCGHSA enrichment
Show 24 more
  1. 2026-08-09 08:14 UTCGHSA enrichment
  2. 2026-08-09 03:59 UTCGHSA enrichment
  3. 2026-08-08 11:20 UTCGHSA enrichment
  4. 2026-08-08 06:25 UTCGHSA enrichment
  5. 2026-08-08 02:10 UTCGHSA enrichment
  6. 2026-08-07 21:56 UTCGHSA enrichment
  7. 2026-08-07 17:41 UTCGHSA enrichment
  8. 2026-08-07 13:24 UTCGHSA enrichment
  9. 2026-08-06 17:28 UTCGHSA enrichment
  10. 2026-08-06 12:06 UTCGHSA enrichment
  11. 2026-08-06 07:51 UTCGHSA enrichment
  12. 2026-08-06 03:36 UTCGHSA enrichment
  13. 2026-08-05 23:21 UTCGHSA enrichment
  14. 2026-08-04 06:05 UTCGHSA enrichment
  15. 2026-08-04 01:49 UTCGHSA enrichment
  16. 2026-08-03 21:34 UTCGHSA enrichment
  17. 2026-08-03 01:56 UTCGHSA enrichment
  18. 2026-08-02 21:42 UTCGHSA enrichment
  19. 2026-08-02 17:27 UTCGHSA enrichment
  20. 2026-08-02 13:12 UTCEG score recompute
  21. 2026-08-02 13:12 UTCGHSA enrichment
  22. 2026-07-23 03:19 UTCEG score recompute
  23. 2026-07-08 17:45 UTCEG score recompute
  24. 2026-07-08 17:45 UTCGHSA enrichment

Frequently asked(4)

What is CVE-2026-54334?
CVE-2026-54334 is a critical vulnerability published on April 16, 2026. UEFI Firmware Parser parses BIOS, Intel ME, and UEFI firmware structures including volumes, file systems, and files. Prior to 1.14, ReadCLen() in uefifirmware/compression/Tiano/Decompress.c reads Number from GetBits(Sd, CBIT) with CBIT = 9 and can obtain 511 entries for the 510-element Sd->mCLen…
When was CVE-2026-54334 disclosed?
CVE-2026-54334 was first published in the National Vulnerability Database on April 16, 2026, with the most recent update on September 14, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
What is the CVSS score of CVE-2026-54334?
CVE-2026-54334 has a CVSS v3 base score of 9.8 (NVD).
How do I remediate CVE-2026-54334?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-54334, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-54334

Explore →

Is Your Infrastructure Affected by CVE-2026-54334?

EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.

Start Free Scan →Browse All CVEs