Medium severity · published Oct 8, 2026
CVE-2026-107738
SumatraPDF: Untrusted binary record offset used without lower-bound validation
6.8
CVSS
0.1%
EPSS
No
On KEV
Description
SumatraPDF is a multi-format reader for Windows. In 3.6.1 and earlier, ChmFile::GetCharZ() narrows file-controlled unsigned string offsets from /#WINDOWS and /#IVB to signed integers without a lower-bound check. An offset that becomes negative can make the function read before the /#STRINGS buffer, causing deterministic application termination. No broader impact is claimed beyond the advisory-supported conditions. No fixed version is available as of this review.
Exploitation
Is it being used?
Exploit prediction (EPSS)0.1% · higher than 2% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
SU
sumatrapdf · sumatrapdfreader
<= 3.6.1 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-107738
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-107738
x_refsource_CONFIRM
https://github.com/sumatrapdfreader/sumatrapdf/security/advisories/GHSA-33jg-vxm6-8mxx
x_refsource_MISC
https://github.com/sumatrapdfreader/sumatrapdf/commit/62254ed6d781ceb5cd16489bb423e7f591cd72c4
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