CVE-2026-107731: sumatrapdfreader sumatrapdf Out-of-bounds Read

Vulnerability summary

CVE-2026-107731 is a medium (CVSS 5.5) Out-of-bounds Read vulnerability in sumatrapdfreader sumatrapdf. EPSS estimates a 0.11% chance of exploitation in the next 30 days, higher than 1.3% of scored vulnerabilities.

Timeline

1. 08-10-2026
   PublishedVulnerability first disclosed.
2. 09-10-2026
   Last modifiedVulnerability information updated.

Description

SumatraPDF is a multi-format reader for Windows. In 3.7.0.22298, four independently reachable range-validation variants in src/LitDoc.cpp allow file-controlled offsets and sizes to overflow, narrow to negative values, or wrap before incomplete bounds checks. The affected calculations include contentOffset, the directory expression dirOff64 + dirLen64, and the decoded-section offset + size, along with secondary-header range handling. Opening a crafted LIT file that reaches one of these variants can cause invalid pointer reads and deterministic application termination. No broader impact is claimed beyond the advisory-supported conditions. No fixed version is available as of this review.

• CWE-125Out-of-bounds ReadThe product reads data past the end, or before the beginning, of the intended buffer.