- 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.
- Source
- security-advisories@github.com
- NVD status
- Received
CVSS 3.1
- Type
- Secondary
- Base score
- 6.6
- Impact score
- 4.7
- Exploitability score
- 1.8
- Vector string
- CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:L
- Severity
- MEDIUM
- security-advisories@github.com
- CWE-119
- Hype score
- Not currently trending