What is CVE-2026-23951?

CVE-2026-23951 is a medium-severity vulnerability in Sumatrapdfreader Sumatrapdf, classified under Out-of-bounds Read. CVSS score: 5.5/10. Published 2026-01-22.

How severe is CVE-2026-23951?

Medium severity. CVSS v3 base score is 5.5 out of 10.

Out-of-bounds Read in Sumatrapdfreader Sumatrapdf

CVE-2026-23951

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 PalmDbRead…

Vulnerability class: Buffer Overflow

EPSS: 0.002 (9.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.

Affected products

Sumatrapdfreader Sumatrapdf — versions <= 3.5.2rel

Weakness classification (CWE)

References

security-advisories@github.com (x_refsource_CONFIRM, Exploit, Vendor Advisory)
security-advisories@github.com (Product, x_refsource_MISC)

Frequently asked questions

What is CVE-2026-23951?: CVE-2026-23951 is a medium-severity vulnerability in Sumatrapdfreader Sumatrapdf, classified under Out-of-bounds Read. CVSS score: 5.5/10. Published 2026-01-22.
How severe is CVE-2026-23951?: Medium severity. CVSS v3 base score is 5.5 out of 10.