CVE-2026-23951

Name: CVE-2026-23951
Creator: NVD / NIST
Published: 2026-01-22T01:15:52.633+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.5/10EPSS 0.19%

Last modified Jun 17, 2026

CVE-2026-23951 is a medium-severity vulnerability rated 5.5/10 on the CVSS scale. 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. EPSS estimates a 0.19% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

5.5/10

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

EPSS Probability

0.19%

9.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Sumatrapdfreader	Sumatrapdf	All versions

References

https://github.com/sumatrapdfreader/sumatrapdf/blob/master/src/PalmDbReader.cppProduct
https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-hj4w-c5x8-p2hvExploit, Vendor Advisory

Timeline

Published: Jan 22, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-23951?

How severe is CVE-2026-23951?

CVE-2026-23951 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.19% probability of exploitation in the next 30 days.

How do I fix CVE-2026-23951?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-23951?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST