Vulnerability record · CVE-2026-34743 · published 2 April 2026

CVE-2026-34743: Tukaani xz heap-based buffer overflow vulnerability

Tukaani · Xz

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.

1.7 CVSS 4.0 Low EPSS 0.57% · top 54.9% CWE-122 · Heap-based buffer overflow

1.7CVSS 4.0 base score

0.57%EPSS exploitation probability, 30 days

NoNot in CISA KEV

1Affected product versions listed by NVD

5References

24 Jul 2026Last modified by NVD

Description

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/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:

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

Xz Tukaani

References

Link	Tags
https://github.com/tukaani-project/xz/commit/c8c22869e780ff57c96b46939c3d79ff99395f87	Patch
https://github.com/tukaani-project/xz/releases/tag/v5.8.3	ProductRelease Notes
https://github.com/tukaani-project/xz/security/advisories/GHSA-x872-m794-cxhv	Vendor Advisory
http://www.openwall.com/lists/oss-security/2026/03/31/13	Mailing ListPatchThird Party Advisory
https://lists.debian.org/debian-lts-announce/2026/07/msg00034.html

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-34743), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.