CVE-2026-34743: Tukaani Xz

Medium severity, CVSS 5.3. EPSS: 0.6% chance of exploitation in the next 30 days.

XZ Utils provide a general-purpose data-compression library plus command-line tools. Prior to version 5.8.3, if lzma_index_decoder() was used to decode an Index that contained no Records, the resulting lzma_index was left in a state where where a subsequent lzma_index_append() would allocate too little memory, and a buffer overflow would occur. This issue has been patched in version 5.8.3.

Affected products

• Tukaani Xz: before 5.8.3 (fixed in 5.8.3)

Published 2026-04-02. Last modified 2026-07-24.