CVE-2026-23951 — MEDIUM (5.5)

Vulnerability 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.

CVSS Score

5.5

MEDIUM

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

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

REQUIRED

Scope

UNCHANGED

Confidentiality

NONE

Integrity

NONE

Availability

HIGH

Affected Products

Vendor	Product	Versions
Sumatrapdfreader	Sumatrapdf	-

Related Weaknesses (CWE)

CWE-191 CWE-193 CWE-125

References

https://github.com/sumatrapdfreader/sumatrapdf/blob/master/src/PalmDbReader.cppProduct
https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-hj4w-c5xExploitVendor Advisory

FAQ

What is CVE-2026-23951?

CVE-2026-23951 is a vulnerability with a CVSS score of 5.5 (MEDIUM). 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 cal...

How severe is CVE-2026-23951?

CVE-2026-23951 has been rated MEDIUM with a CVSS base score of 5.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-23951?

Check the references section above for vendor advisories and patch information. Affected products include: Sumatrapdfreader Sumatrapdf.