CVEvulnerability

CVE-2026-55586

6.6 MEDIUM Published 2026-08-20 Modified 2026-10-18 Official page ↗
Status
Deferred
Published
2026-08-20
Last modified
2026-10-18
Assigner
[email protected]
CVSS 3.1 ([email protected])
6.6 MEDIUM — CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:L
Weaknesses
CWE-119, CWE-787

Description

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 make_decode_table in ext/CHMLib/lzx.c. In the long-code branch, the function writes new internal nodes through next_symbol before validating that the canonical Huffman table has overflowed. The PRETREE case can write beyond the 104-entry PRETREE_table into adjacent heap state in struct LZXstate when reached through chm_open, chm_retrieve_object, LZXdecompress, and BUILD_TABLE. This produces heap memory corruption in the parser process, while arbitrary code execution has not been demonstrated. No fixed version is available as of this review.

Related

Weakness · CWE (2)

  • CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer weakness
  • CWE-787 Out-of-bounds Write weakness

References