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VulnerabilityPublished Updated

CVE-2026-26054: sumatrapdfreader sumatrapdf · Out-of-bounds Read

Affects sumatrapdfreader sumatrapdfSource CVE Database V5

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Not known to be exploited · CVSS 6.8 Medium : upgrade to 3.6 when convenient.

Data as of 6 Nov 2026, 23:24 UTC

CVSS 4.0 base score
6.8Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 3.6
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.

What to do

Upgrade sumatrapdf and sumatrapdfreader/sumatrapdf to 3.6.

Affected software

ProductAffectedFixed in
sumatrapdfreadersumatrapdfAffected
  • <3.6
Fixed in
  • 3.6
GitHubsumatrapdfreader/sumatrapdfpkg:github/sumatrapdfreader/sumatrapdfOther threatsAffected
  • <3.6
Fixed in
  • 3.6

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

This vulnerability is fixed in SumatraPDF version 3.6. Users should upgrade to version 3.6 or later to remediate this issue. No additional mitigation steps are indicated.

Description

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.

References

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