CVE-2026-25920
Undergoing Analysis Undergoing Analysis - In Progress
Heap Out-of-Bounds Read in SumatraPDF MOBI Decompressor Causes Crash

Publication date: 2026-02-09

Last updated on: 2026-02-20

Assigner: GitHub, Inc.

Description
SumatraPDF is a multi-format reader for Windows. In 3.5.2 and earlier, a heap out-of-bounds read vulnerability exists in SumatraPDF's MOBI HuffDic decompressor. The bounds check in AddCdicData() only validates half the range that DecodeOne() actually accesses. Opening a crafted .mobi file can read nearly (1 << codeLength) bytes beyond the CDIC dictionary buffer, leading to a crash.
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Meta Information
Published
2026-02-09
Last Modified
2026-02-20
Generated
2026-06-16
AI Q&A
2026-02-10
EPSS Evaluated
2026-06-14
NVD
CVE-2026-25920
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
sumatrapdfreader sumatrapdf to 3.5.2 (inc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-125 The product reads data past the end, or before the beginning, of the intended buffer.
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Executive Summary

This vulnerability exists in SumatraPDF version 3.5.2 and earlier, specifically in the MOBI HuffDic decompressor component. The issue is a heap out-of-bounds read caused by improper bounds checking in the AddCdicData() function. This function only validates half the range that the DecodeOne() function actually accesses. As a result, when a specially crafted .mobi file is opened, the program can read memory beyond the intended CDIC dictionary buffer.

This out-of-bounds read can lead to a crash of the SumatraPDF application.

Impact Analysis

The primary impact of this vulnerability is that opening a maliciously crafted .mobi file can cause SumatraPDF to crash due to the heap out-of-bounds read. This results in a denial of service (DoS) condition where the application becomes unavailable or unstable.

There is no indication from the provided information that this vulnerability leads to information disclosure, privilege escalation, or code execution.

Compliance Impact

I don't know

Detection Guidance

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Mitigation Strategies

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