Description
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.
Published: 2026-10-08
Score: 5.5 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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History

Fri, 09 Oct 2026 16:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 09 Oct 2026 00:00:00 +0000

Type Values Removed Values Added
First Time appeared Sumatrapdfreader
Sumatrapdfreader sumatrapdf
Vendors & Products Sumatrapdfreader
Sumatrapdfreader sumatrapdf

Thu, 08 Oct 2026 22:30:00 +0000

Type Values Removed Values Added
Description 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.
Title SumatraPDF: Unsigned-to-signed hdrLen validation bypass in SumatraPDF MOBI parsing causes out-of-bounds read
Weaknesses CWE-125
References
Metrics cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H'}


Subscriptions

Sumatrapdfreader Sumatrapdf
cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-10-09T15:46:45.488Z

Reserved: 2026-10-08T17:21:52.976Z

Link: CVE-2026-107729

cve-icon Vulnrichment

Updated: 2026-10-09T15:46:41.964Z

cve-icon NVD

Status : Deferred

Published: 2026-10-08T23:16:58.350

Modified: 2026-10-09T16:17:24.003

Link: CVE-2026-107729

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-08T23:45:16Z

Weaknesses