Unrated severityOSV Advisory· Published Jan 22, 2026· Updated Jan 22, 2026
SumatraPDF's Integer Underflow in PalmDbReader Leads to Crash
CVE-2026-23951
Description
SumatraPDF is a multi-format reader for Windows. All versions contain an off-by-one error in the validation code that only triggers with exactly 2 records, causing an integer underflow in the size calculation. This bug exists in PalmDbReader::GetRecord when opening a crafted Mobi file, resulting in an out-of-bounds heap read that crashes the app. There are no published fixes at the time of publication.
Affected products
1- Range: 1.4split, 1.5split, 1.6split, …
Patches
0No patches discovered yet.
Vulnerability mechanics
AI mechanics synthesis has not run for this CVE yet.
References
2- github.com/sumatrapdfreader/sumatrapdf/blob/master/src/PalmDbReader.cppmitrex_refsource_MISC
- github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-hj4w-c5x8-p2hvmitrex_refsource_CONFIRM
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