CVE-2026-23951CWE-125CWE-191

SumatraPDF's Integer Underflow in PalmDbReader Leads to Crash

Medium · published January 22, 2026

CVSS v3.1
5.5
EPSS
0%
Percentile
12.0
In the wild
Unconfirmed
What it is

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.

The record
Technical detail
CVSS v3.1
5.5 · MEDIUM
Vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.00221 · 12.0th percentile
Weaknesses
CWE-125 · Out-of-bounds Read; CWE-191 · Integer Underflow (Wrap or Wraparound)
Published
2026-01-22T00:17Z
EPSS history
Timeline
  • 22 JAN 00:17Z
    SumatraPDF's Integer Underflow in PalmDbReader Leads to Crash
    cvelistv5