CVE-2026-54334

CRITICALPre-NVD 9.89.8
EchelonGraph scoreMEDIUM confidence

“—” beside the score: it is equal to the CVSS score beside it.

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: EPSS, GitHub Security Advisory, a secondary CVSS source
Trending — 3 sources updated this week

Also known asEUVD-2026-78065 (ENISA EUVD) · GHSA-hm2w-vr2p-hq7w (GitHub Security Advisories)Source: ENISA EUVD

9.8EG
EchelonGraph verdictPlan a fixRemediate within your standard update timelines at low or medium mission impact and sooner than that at high (the SSVC decision on this page).
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.8%CVSS: 9.8Exploit: None knownExposed services: Not assessed

A fix is available — apply it.

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
9.8CRITICALmedium confidence
EG Risk
59
EG Risk 59/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.

How it’s computed (value × EchelonGraph’s weight)
Severity98% × 45%
Impact severity (EG Severity): CVSS 9.8 of 10. Never the KEV-floored or EPSS-lifted EG Score.
Exploitation0.8% × 40%
FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.
Automatability100% × 15%
CISA's SSVC Automatable value: yes (Vulnrichment).
SSVC (CISA's decision table, applied by EchelonGraph): Track at low or medium mission impact; Attend at high (mission-essential systems).
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.8%
EPSS %ILE
56th
KEV
Not listed

What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)

The EG score (9.8): severity, escalated by confirmed exploitation. This CVE's 9.8 is its impact severity (EG Severity), not escalated.

EG Severity
9.8 CRITICALCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
EG Likelihood
0.8% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-10-29). FIRST's exploitation probability, not an EchelonGraph model.
Confirmed exploitation
None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
EG Priority
SSVC Track at medium mission impactTrack at low or medium mission impact; Attend at high (mission-essential systems).CISA BOD 26-04: 3 days if the affected system is publicly exposed; 60 days if it is not.Each input and its source: the SSVC and BOD 26-04 blocks below.

SSVC (CISA's decision table, applied by EchelonGraph)Track at low or medium mission impact; Attend at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table

BOD 26-04 (CISA's remediation timeline, Table 1)3 days if the affected system is publicly exposed; 60 days if it is not.

In CISA KEV no (CISA's KEV catalog) · Automatable yes (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it

Published

April 16, 2026

Last Modified

September 30, 2026

Advisory Details (3)

Auto-updated Oct 15, 2026
Patch available. Sources: github_commit, github_pr, github.
GitHub advisoryMentions a patch (unverified)

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 pull request 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 / EcosystemFix (by version range) / 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 rangeFix by version rangeDependents
uefi-firmware1.1 ... 1.9 (10 versions)
  • every version through 1.12: no fix on record
—

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 23× in last 7d / 73× in last 30d)

Each row is a time one of our pipelines fetched, updated or re-scored this CVE. 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. An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). Most recent first.

Showing the most recent 100 of 140 refreshes on record for this CVE.

A repeat, a row identical to one the same pipeline wrote less than 10 seconds earlier, is not a separate refresh and is not counted. None are among the latest 100 rows. The 40 oldest rows on record are not shown and were not checked, so the counts can still include repeats.

  1. 2026-10-30 16:34 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  2. 2026-10-30 12:49 UTCEG score recompute
  3. 2026-10-30 12:48 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  4. 2026-10-29 16:33 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  5. 2026-10-29 14:31 UTCEG score recompute
  6. 2026-10-29 14:30 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  7. 2026-10-28 16:32 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  8. 2026-10-28 16:20 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  9. 2026-10-27 18:10 UTCEG score recompute
  10. 2026-10-27 18:10 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  11. 2026-10-27 16:32 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  12. 2026-10-26 20:00 UTCEG score recompute
  13. 2026-10-26 20:00 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  14. 2026-10-26 16:31 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  15. 2026-10-25 19:49 UTCEG score recompute
  16. 2026-10-25 19:48 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  17. 2026-10-25 16:33 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  18. 2026-10-25 14:19 UTCEG score recompute
  19. 2026-10-24 21:36 UTCEG score recompute
  20. 2026-10-24 21:36 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  21. 2026-10-24 16:33 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  22. 2026-10-23 23:26 UTCEG score recompute
  23. 2026-10-23 23:25 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  24. 2026-10-23 16:32 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  25. 2026-10-23 01:01 UTCEG score recompute
Show 75 more
  1. 2026-10-23 01:01 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  2. 2026-10-22 16:34 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  3. 2026-10-22 02:18 UTCEG score recompute
  4. 2026-10-22 02:18 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  5. 2026-10-21 16:33 UTCEPSS rescoreEPSS 0.8% · 56th percentile
  6. 2026-10-21 03:50 UTCEG score recompute
  7. 2026-10-21 03:50 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  8. 2026-10-20 16:33 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  9. 2026-10-20 05:36 UTCEG score recompute
  10. 2026-10-20 05:35 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  11. 2026-10-19 16:32 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  12. 2026-10-19 07:14 UTCEG score recompute
  13. 2026-10-19 07:14 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  14. 2026-10-18 16:32 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  15. 2026-10-18 09:00 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  16. 2026-10-18 03:31 UTCEG score recompute
  17. 2026-10-17 16:34 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  18. 2026-10-17 10:46 UTCEG score recompute
  19. 2026-10-17 10:46 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  20. 2026-10-16 16:42 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  21. 2026-10-16 12:23 UTCEG score recompute
  22. 2026-10-16 12:23 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  23. 2026-10-15 16:32 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  24. 2026-10-15 14:09 UTCEG score recompute
  25. 2026-10-15 14:08 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  26. 2026-10-14 16:33 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  27. 2026-10-14 08:53 UTCEG score recompute
  28. 2026-10-14 08:53 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  29. 2026-10-13 16:34 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  30. 2026-10-13 05:09 UTCEG score recompute
  31. 2026-10-13 05:09 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  32. 2026-10-12 16:34 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  33. 2026-10-12 15:56 UTCEG score recompute
  34. 2026-10-12 06:57 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  35. 2026-10-11 19:39 UTCEG score recompute
  36. 2026-10-11 16:54 UTCEG score recompute
  37. 2026-10-11 14:18 UTCEG score recompute
  38. 2026-10-11 13:49 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  39. 2026-10-10 20:00 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  40. 2026-10-09 20:07 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  41. 2026-10-08 17:12 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  42. 2026-10-07 23:48 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  43. 2026-10-06 15:18 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  44. 2026-10-05 17:43 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  45. 2026-10-04 23:22 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  46. 2026-10-03 14:26 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  47. 2026-10-02 17:56 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  48. 2026-10-01 19:50 UTCEPSS rescoreEPSS 0.8% · 55th percentile
  49. 2026-09-30 18:13 UTCEG score recompute
  50. 2026-09-30 18:13 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  51. 2026-09-30 15:03 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  52. 2026-09-29 15:22 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  53. 2026-09-28 13:51 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  54. 2026-09-27 13:48 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  55. 2026-09-26 15:59 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  56. 2026-09-24 14:04 UTCEPSS rescoreEPSS 0.8% · 54th percentile
  57. 2026-09-23 17:54 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  58. 2026-09-20 20:16 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  59. 2026-09-18 19:28 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  60. 2026-09-17 19:31 UTCEPSS rescoreEPSS 0.4% · 37th percentile
  61. 2026-09-16 19:26 UTCEG score recompute
  62. 2026-09-16 19:26 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  63. 2026-09-16 18:53 UTCEG score recompute
  64. 2026-09-16 18:53 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  65. 2026-09-16 14:08 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  66. 2026-09-16 05:15 UTCEPSS rescoreEPSS 0.4% · 36th percentile
  67. 2026-09-14 20:27 UTCEG score recompute
  68. 2026-09-14 20:27 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  69. 2026-09-14 20:16 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  70. 2026-08-16 10:52 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  71. 2026-08-16 06:37 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  72. 2026-08-14 22:26 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  73. 2026-08-14 18:12 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  74. 2026-08-14 13:11 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8
  75. 2026-08-14 08:57 UTCGHSA enrichmentGHSA-hm2w-vr2p-hq7w · GitHub severity CRITICAL · GitHub CVSS 9.8

Frequently asked(5)

What is CVE-2026-54334?
CVE-2026-54334 is a critical-severity vulnerability; its CVE record was 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 the CVE record for CVE-2026-54334 published?
The CVE record for CVE-2026-54334 was published on April 16, 2026. That is the record's publication date; the vulnerability itself may have been made public earlier. EchelonGraph's copy of the record carries a last-modified date of September 30, 2026; the record at its source may have been updated since.
Is CVE-2026-54334 actively exploited?
CVE-2026-54334 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.8% probability of exploitation in the next 30 days (56th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-54334?
CVE-2026-54334 has a CVSS base score of 9.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-54334?
A fix for CVE-2026-54334 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-54334 are linked in the Vendor Advisories panel on this page.

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