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Medium · 5.5 CVE-2026-25920 EUVD-2026-6260

SumatraPDF has a heap out-of-bounds read in MOBI HuffDic decompressor

Published Feb 9, 2026 · Updated Feb 11, 2026 · Assigned by GitHub_M

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.

Affected products

VendorProductAffectedFixed
sumatrapdfreader sumatrapdf <= 3.5.2 —

References