CVE-2025-31115 | XZ has a heap-use-after-free bug in threaded .xz decoder

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.

Published: 2025-04-03 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Deferred，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-31115 is rated Moderate Risk (50.5/100): CVSS High severity, with low exploitation likelihood (EPSS 0.59%). Review affected assets and schedule remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-31115

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.04% 0.59% +0.55%
2 2026-05-12 0.31% 0.04% -0.27%
3 2026-01-28 — 0.31% —

Full EPSS history (6 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-31115

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.7 4.0 HIGH
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network.
Attack complexity (AC:L)
Exploitation conditions are straightforward and stable.
Attack requirements (AT:N)
No additional preconditions are required beyond normal reachability.
Privileges required (PR:N)
No privileges are required.
User interaction (UI:N)
No user interaction is required.
Vulnerable system confidentiality impact (VC:N)
No confidentiality impact on the vulnerable system.
Vulnerable system integrity impact (VI:N)
No integrity impact on the vulnerable system.
Vulnerable system availability impact (VA:H)
High availability impact on the vulnerable system.
Subsequent system confidentiality impact (SC:N)
No confidentiality impact on subsequent systems.
Subsequent system integrity impact (SI:N)
No integrity impact on subsequent systems.
Subsequent system availability impact (SA:N)
No availability impact on subsequent systems.
Exploit maturity (threat) (E:X)
Not defined: no reliable threat intelligence; scoring assumes the worst case (equivalent to Attacked).
Confidentiality requirement (CR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Integrity requirement (IR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Availability requirement (AR:X)
Not defined: insufficient information; scoring treats this like High (worst case).
Modified attack vector (MAV:X)
Not defined: scoring uses the Base Attack Vector (AV).
Modified attack complexity (MAC:X)
Not defined: scoring uses the Base Attack Complexity (AC).
Modified attack requirements (MAT:X)
Not defined: scoring uses the Base Attack Requirements (AT).
Modified privileges required (MPR:X)
Not defined: scoring uses the Base Privileges Required (PR).
Modified user interaction (MUI:X)
Not defined: scoring uses the Base User Interaction (UI).
Modified vulnerable system confidentiality impact (MVC:X)
Not defined: scoring uses the Base VC metric.
Modified vulnerable system integrity impact (MVI:X)
Not defined: scoring uses the Base VI metric.
Modified vulnerable system availability impact (MVA:X)
Not defined: scoring uses the Base VA metric.
Modified subsequent system confidentiality impact (MSC:X)
Not defined: scoring uses the Base SC metric.
Modified subsequent system integrity impact (MSI:X)
Not defined: scoring uses the Base SI metric.
Modified subsequent system availability impact (MSA:X)
Not defined: scoring uses the Base SA metric.
Safety (supplemental) (S:X)
Not evaluated.
Automatable (supplemental) (AU:X)
Not evaluated.
Recovery (supplemental) (R:X)
Not evaluated.
Value density (supplemental) (V:X)
Not evaluated.
Vulnerability response effort (supplemental) (RE:X)
Not evaluated.
Provider urgency (supplemental) (U:X)
Not evaluated.
 — — [email protected]

Weakness enumeration for CVE-2025-31115

OS Trackers for CVE-2025-31115

vendor priority summary link
alpine high CVE-2025-31115: 1 source package rows (xz); 20 state rows across 7 repos (3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, 3.23-main, edge-main); fixed 13, open 7. https://security.alpinelinux.org/vuln/CVE-2025-31115
debian unimportant CVE-2025-31115 unimportant priority: Debian including 1 source packages (xz-utils), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2025-31115
gentoo normal CVE-2025-31115: 1 GLSA(s) (202504-01), 1 atom(s) (app-arch/xz-utils); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2025-31115
redhat high — https://access.redhat.com/security/cve/CVE-2025-31115
suse high CVE-2025-31115 severity important: SUSE including 377 source package names (0.0.17-1.1:liblzma5-5.4.1-150600.3.3.1, 0.1.6-1.2:liblzma5-5.4.1-150600.3.3.1, …), 958 product×package rows across 284 product lines (Container bci/gcc, Container bci/golang, … (284 product lines)): Fixed 603, Known Affected 231, Known Not Affected 124. https://www.suse.com/security/cve/CVE-2025-31115/
ubuntu medium CVE-2025-31115 medium priority: Ubuntu including 1 source packages (xz-utils), 9 status rows across 9 suites (bionic, focal, jammy, noble, oracular, plucky, trusty, upstream, xenial): not-affected 5, released 4. https://ubuntu.com/security/CVE-2025-31115

Affected software / configurations for CVE-2025-31115

Vendor Product Version Raw CPE
No affected products in dataset.

References for CVE-2025-31115

cvelogic Threat Intelligence