CVE-2026-125742

Description

7-Zip before 26.06 contains a heap out-of-bounds write vulnerability in the LZX decoder that lets attackers corrupt memory when a continuation CAB volume declares a smaller window. Attackers can entice victims to extract crafted multi-volume CAB archives, where a stale _pos value bypasses bounds checks, enabling arbitrary code execution.

References

• https://github.com/ip7z/7zip/blob/26.05/CPP/7zip/Compress/LzxDecoder.cpp#L1496-L1513
• https://github.com/ip7z/7zip/commit/d3296e39e1f1f92c7b41c0c3848e65640428d42d
• https://github.com/ip7z/7zip/releases/tag/26.06
• https://potion-brew.pages.dev/posts/7zip-cab-lzx-window-desync-rce/
• https://www.vulncheck.com/advisories/7-zip-before-26.06-heap-out-of-bounds-write-via-lzx-decoder-in-cab-extraction