CVE-2026-23951 MEDIUM

CVE-2026-23951: SumatraPDF's Integer Underflow in PalmDbReader Leads to Crash

Vendor Sumatrapdfreader
Product sumatrapdf
Weakness CWE-125
Published January 22, 2026
Last update January 22, 2026

CVSS base score

5.5/10
Attack vector Local
Attack complexity Low
Privileges required None
User interaction Required
Confidentiality None
Integrity None

CVSS vector

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

What the vulnerability does

01Description

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.

Key dates

02Disclosure timeline

January 22, 2026 CVE published
January 22, 2026 Record updated