Out-of-bounds Read in Sumatrapdfreader Sumatrapdf
CVE-2026-107729
SumatraPDF is a multi-format reader for Windows. In 3.7.0.22298, src/MobiDoc.cpp narrows the untrusted unsigned mobiHdr.hdrLen field to a signed integer for validation; values above INT_MAX become negative and bypass the upper-bound check. When the EXTH flag is set, the original unsigned value is reused as a pointer offset, causing DecodeExthHeader() to read beyond the record buffer. Opening a crafted MOBI file can reliably terminate the application with a native access violation; no code execution, information disclosure, or integrity impact has been demonstrated. No fixed version is available as of this review.
Vulnerability class: Buffer Overflow
Published · last modified .
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.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
- Sumatrapdfreader Sumatrapdf — versions <= 3.7.0.22298
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-107729?
- CVE-2026-107729 is a medium-severity vulnerability in Sumatrapdfreader Sumatrapdf, classified under Out-of-bounds Read. CVSS score: 5.5/10. Published 2026-10-08.
- How severe is CVE-2026-107729?
- Medium severity. CVSS v3 base score is 5.5 out of 10.