CVE-2025-31115

A flaw was found in the XZ Utils library. In affected versions, the multithreaded .xz decoder in liblzma has a bug where invalid input can trigger a heap use-after-free condition, allowing writes to an address based on the null pointer plus an offset. This issue may result in a crash or other undefined behavior. Applications and libraries that use the lzma_stream_decoder_mt function are affected.

This vulnerability is rated as important severity because a flaw exists in XZ Utils multithreaded .xz decoder within liblzma. When processing specially crafted compressed input, the decoder can trigger a heap use-after-free condition and perform memory writes to an address calculated from a null pointer plus an offset. These issues can reliably cause application crashes, leading to denial of service, and may allow memory corruption that affects process stability and security. Systems or applications decompressing untrusted .xz data with multithreaded decoding are at heightened risk of disruption and compromise.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.