CVE-2026-107729

5.5 MEDIUM 0.1% exploit odds Fix listed Memory safety OS & kernel

What it is

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.

At a glance

Exploitability: Can be exploited locally on the machine without logging in, but needs a user to act. High risk of service disruption.
Exploit odds: 0.1% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-10-08 23:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-10-09 16:17 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.1% in the next 30 days (EPSS).
Severity: 5.5 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-10-08 23:16 UTC
Last modified: 2026-10-09 16:17 UTC
Exploit probability: 0.1% · EPSS, next 30 days
Weakness: CWE-125 · Out-of-bounds read
Record status: Deferred

Attack profile CVSS 3.1 · 5.5

Attack vector: Local
Complexity: Low
Privileges needed: None
User interaction: Required
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Raw vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-107729.md and follow it. Check whether this project is affected by CVE-2026-107729. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record