CVE-2026-55586

SumatraPDF is a multi-format reader for Windows. In 3.6.1 and earlier, a crafted CHM file can supply malformed LZX Huffman code lengths to makedecodetable in ext/CHMLib/lzx.c. In the long-code branch, the function writes new internal nodes through nextsymbol before validating that the canonical...

EUVD-2026-63469

SumatraPDF is a multi-format reader for Windows. In 3.6.1 and earlier, a crafted CHM file can supply malformed LZX Huffman code lengths to makedecodetable in ext/CHMLib/lzx.c. In the long-code branch, the function writes new internal nodes through nextsymbol before validating that the canonical...

CVE-2026-55586 SumatraPDF: Heap out-of-bounds write in vendored CHMLib LZX Huffman table construction reachable from crafted CHM files

SumatraPDF is a multi-format reader for Windows. In 3.6.1 and earlier, a crafted CHM file can supply malformed LZX Huffman code lengths to makedecodetable in ext/CHMLib/lzx.c. In the long-code branch, the function writes new internal nodes through nextsymbol before validating that the canonical...

Kaspersky AntiVirus - CHM Parsing Stack Buffer Overflow

Source: https://code.google.com/p/google-security-research/issues/detail?id=524 Fuzzing CHM files with Kaspersky Antivirus produced the attached crash. 83c.fec: Access violation - code c0000005 first chance First chance exceptions are reported before any exception handling. This exception may be...

Multiple ClamAV antivirus security vulnerabilities

Buffer overflow on PE files parsing, DoS on CHM parsing...