CVE-2025-31115: XZ has a heap-use-after-free bug in threaded .xz decoder
Description
XZ Utils provide a general-purpose data-compression library plus command-line tools. In XZ Utils 5.3.3alpha to 5.8.0, the multithreaded .xz decoder in liblzma has a bug where invalid input can at least result in a crash. The effects include heap use after free and writing to an address based on the null pointer plus an offset. Applications and libraries that use the lzma_stream_decoder_mt function are affected. The bug has been fixed in XZ Utils 5.8.1, and the fix has been committed to the v5.4, v5.6, v5.8, and master branches in the xz Git repository. No new release packages will be made from the old stable branches, but a standalone patch is available that applies to all affected releases.
Classification
CVE ID: CVE-2025-31115
CVSS Base Severity: HIGH
CVSS Base Score: 8.7
CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Problem Types
CWE-366: Race Condition within a Thread CWE-416: Use After Free CWE-476: NULL Pointer Dereference CWE-826: Premature Release of Resource During Expected LifetimeAffected Products
Vendor: tukaani-project
Product: xz
Exploit Prediction Scoring System (EPSS)
EPSS Score: 0.12% (probability of being exploited)
EPSS Percentile: 31.97% (scored less or equal to compared to others)
EPSS Date: 2025-05-02 (when was this score calculated)
References
https://nvd.nist.gov/vuln/detail/CVE-2025-31115https://github.com/tukaani-project/xz/security/advisories/GHSA-6cc8-p5mm-29w2
https://github.com/tukaani-project/xz/commit/d5a2ffe41bb77b918a8c96084885d4dbe4bf6480
https://tukaani.org/xz/xz-cve-2025-31115.patch