CVE-2026-107731 SumatraPDF: LIT parser range-validation flaws cause invalid-pointer reads and denial of service
Attackers can cause application termination via crafted LIT files due to range-validation flaws in SumatraPDF's parser.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-107731?
CVE-2026-107731 is a medium-severity denial of service vulnerability in sumatrapdfreader sumatrapdf, published on 8 Oct 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official 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.
Weakness: CWE-125
Which versions are affected by CVE-2026-107731?
How do I fix CVE-2026-107731?
No fix has been published for CVE-2026-107731 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-107731 being exploited?
There is no known exploitation of CVE-2026-107731 in the wild and no public exploit code.
Sources
Also known as GHSA-753j-hx3p-xm9g.