CVE-2026-107735: sumatrapdfreader sumatrapdf Failing Open

Vulnerability summary

CVE-2026-107735 is a medium (CVSS 5.4) Failing Open 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 3.6.1 and earlier, InitializePolicies() starts the sumatrapdfrestrict.ini path with gPolicyRestrictions set to Perm::All and only ORs permission bits, so the INI file never revokes permissions. Deploying SumatraPDF with this INI file, including a malformed file or zero-valued permission settings, can silently bypass configured disk, network, printing, registry, clipboard, preference, and fullscreen restrictions. The -restrict command-line path works correctly and is not affected. No fixed version is available as of this review.

• CWE-636Not Failing Securely ('Failing Open')When the product encounters an error condition or failure, its design requires it to fall back to a state that is less secure than other options that are available, such as selecting the weakest encryption algorithm or using the most permissive access control restrictions.