CVE-2026-26054

MEDIUMPre-NVD 6.86.8—
EchelonGraph scoreMEDIUM confidence

This medium-severity CVE scores 6.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.1% (2nd percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
6.8EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: 0.1%CVSS: 6.8Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

SumatraPDF is a multi-format reader for Windows. Prior to 3.6, the MobiDoc::ParseHeader function in src/MobiDoc.cpp validates a record using kMobiHeaderMinLen but DecodeMobiDocHeader constructs a decoder sized for kMobiHeaderLen without receiving the actual remaining buffer length. A malformed MOBI file can use an attacker-controlled header length to bypass optional-field early returns and cause the decoder to read beyond a short heap buffer. Opening the crafted document can crash SumatraPDF. This issue is fixed in version 3.6.

CVSS v3
6.8
EG Score
6.8MEDIUMmedium confidence
EG Risk
47
EG Risk 47/100CISA SSVC

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
Severity68% × 45%
Exploitation40% × 40%
Automatability0% × 15%
CISA SSVC: Track at low or medium mission impact; Track* at high (mission-essential systems).
Action: A fix is available. Apply it within your standard update timelines.
EPSS PROB
0.1%
EPSS %ILE
2nd
KEV
Not listed

CISA SSVCTrack at low or medium mission impact; Track* at high (mission-essential systems).

A fix is available. Apply it within your standard update timelines.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

September 24, 2026

Last Modified

September 28, 2026

Advisory Details (4)

Auto-updated Sep 24, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_commit, github_release.
github_release Patch Available

3.6 release

Patch available: sumatrapdfreader/sumatrapdf 3.6rel

https://github.com/sumatrapdfreader/sumatrapdf/releases/tag/3.6rel
github_commit Patch Available

commit 24b9ce83383b (sumatrapdfreader/sumatrapdf)

Patch available: sumatrapdfreader/sumatrapdf 3.6rel (contains commit 24b9ce83383b)

https://github.com/sumatrapdfreader/sumatrapdf/commit/24b9ce83383bbaa48b3efe00e4d30cccea126198
generic

crash in mobi file · Issue #5318 · sumatrapdfreader/sumatrapdf · GitHub

https://github.com/sumatrapdfreader/sumatrapdf/issues/5318
github Patch Available🟡 PoC Available

Heap out-of-bounds read in MOBI header parser. · Advisory · sumatrapdfreader/sumatrapdf · GitHub

https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-27p6-wrfp-pgm8

Weakness Classification(1)

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

Data Freshness Timeline

(refreshed 13× in last 7d / 20× 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. 2026-10-05 09:32 UTCEG score recompute
  2. 2026-10-04 23:21 UTCEPSS rescore
  3. 2026-10-04 10:40 UTCEG score recompute
  4. 2026-10-03 14:25 UTCEPSS rescore
  5. 2026-10-03 11:43 UTCEG score recompute
  6. 2026-10-02 12:25 UTCEG score recompute
  7. 2026-10-01 19:49 UTCEPSS rescore
  8. 2026-10-01 13:29 UTCEG score recompute
  9. 2026-09-30 15:03 UTCEPSS rescore
  10. 2026-09-29 15:27 UTCEG score recompute
  11. 2026-09-28 16:34 UTCEG score recompute
  12. 2026-09-28 15:37 UTCEG score recompute
  13. 2026-09-28 13:51 UTCEPSS rescore
  14. 2026-09-27 14:14 UTCEG score recompute
  15. 2026-09-26 15:58 UTCEPSS rescore
  16. 2026-09-26 15:21 UTCEG score recompute
  17. 2026-09-26 00:26 UTCEPSS rescore
  18. 2026-09-24 17:33 UTCEG score recompute
  19. 2026-09-24 16:57 UTCEG score recompute
  20. 2026-09-24 16:56 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-26054?
CVE-2026-26054 is a medium vulnerability published on September 24, 2026. SumatraPDF is a multi-format reader for Windows. Prior to 3.6, the MobiDoc::ParseHeader function in src/MobiDoc.cpp validates a record using kMobiHeaderMinLen but DecodeMobiDocHeader constructs a decoder sized for kMobiHeaderLen without receiving the actual remaining buffer length. A malformed MOBI…
When was CVE-2026-26054 disclosed?
CVE-2026-26054 was first published on September 24, 2026, with the most recent update on September 28, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-26054 actively exploited?
CVE-2026-26054 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.1% probability of exploitation in the next 30 days (2nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-26054?
CVE-2026-26054 has a CVSS base score of 6.8 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-26054?
A fix for CVE-2026-26054 is available: update to the fixed version the vendor names in its advisory.

Dependency Blast Radius

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