SumatraPDF: Unsigned-to-signed hdrLen validation bypass in SumatraPDF MOBI parsing causes out-of-bounds read
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.
CVE-2026-107729
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-107729
sumatrapdf
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"vendor": "sumatrapdfreader",
"product": "sumatrapdf",
"versions": [
{
"status": "affected",
"version": "<= 3.7.0.22298"
}
]
}
]- Related CVEs
- CVE-2026-107729
Source reference:
/cveMetadata/cveId
Publisher severity
medium
Source reference: /containers/cna/metrics
- Event
- #16328 · Revision 1
- Added to Heist Feed
- Publisher date