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TI-2026-21058 Aliases CVE-2026-26054

SumatraPDF: Heap out-of-bounds read in MOBI header parser.

Priority MEDIUM 63CWE-125Published · Updated

Key facts

Attack vector
Local
Privileges required
None
User interaction
Passive
Attack complexity
Low
Attack requirements
None
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-125 and the CVSS impact.

Summary

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.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00209 11th percentileScored 2026-11-07
Fix Fixed sumatrapdf (sumatrapdfreader): 3.6

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
sumatrapdfreadersumatrapdfbefore 3.63.6Patch availableCNA
  • sumatrapdf Vendorsumatrapdfreader Affected before 3.6 Fixed in 3.6 Patch available CNA

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPEVersionsRoleVendor
cpe:2.3:a:sumatrapdfreader:sumatrapdf:*:*:*:*:*:*:*:*——sumatrapdfreader
  • cpe:2.3:a:sumatrapdfreader:sumatrapdf:*:*:*:*:*:*:*:* Versions — — ·sumatrapdfreader

Remediation

  • Fix · CNA sumatrapdf (sumatrapdfreader) Fixed in 3.6

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-26054

References

Other 4

  • TI-2026-18936 SumatraPDF has an Untrusted Search Path in sumatrapdf/src/AppTools.cpp CVSS 3.1HIGH 8.6
  • TI-2025-35489 A null pointer dereference vulnerability was discovered in SumatraPDF 3.5.2 during the… CVSS 3.1HIGH 7.3
  • TI-2012-04514 SumatraPDF 2.1.1/MuPDF 1.0 allows remote attackers to cause an Integer Overflow in the… CVSS 3.1HIGH 7.8
  • TI-2026-69819 Argument injection in SumatraPDF selection translation on Windows CVSS 4.0HIGH 7.1
  • TI-2026-69814 SumatraPDF: SyncTeX Argument Injection in Inverse Search Enables Arbitrary Command Execution via External Editors CVSS 4.0HIGH 7.1
  • TI-2026-69813 Null pointer dereference in SumatraPDF CmdExec crashes the reader CVSS 4.0MEDIUM 6.8
See all 26 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences