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CVE-2026-107729

5.5 · MEDIUM

SumatraPDF is a multi-format reader for Windows.

Published Oct 8, 2026CWE-125EPSS 0.15%

Overview

CVE-2026-107729 is a medium-severity vulnerability. It was published on October 8, 2026 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

Technical description

SumatraPDF is a multi-format reader for Windows. In 3.7.0.22298, src/MobiDoc.cpp narrows the untrusted unsigned mobiHdr.hdrLen field to a signed integer for validation; values above INT_MAX become negative and bypass the upper-bound check. When the EXTH flag is set, the original unsigned value is reused as a pointer offset, causing DecodeExthHeader() to read beyond the record buffer. Opening a crafted MOBI file can reliably terminate the application with a native access violation; no code execution, information disclosure, or integrity impact has been demonstrated. No fixed version is available as of this review.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/sumatrapdfreader/sumatrapdf/commit/1ef900cbad02f06353b0a0747b098ca596f7c131GitHubgithub.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-86hq-m6hv-67h2

How CyberStrike helps

Frequently asked questions

What is CVE-2026-107729?

CVE-2026-107729 is a medium-severity vulnerability. It was published on October 8, 2026 and has a CVSS 3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2026-107729?

This vulnerability has a CVSS 3.1 base score of 5.5, rated MEDIUM. It requires local or adjacent network access to exploit. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-107729?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-107729?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-107729 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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