XZ Utils: Buffer overflow in lzma_index_append()
CVE-2026-34743 is fixed in 7 products on 1 platform, first by liblzma5 5.2.2-1.3ubuntu0.1+esm1, released April 2, 2026. It is not reported as exploited. Patch Radar priority: Routine.
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| liblzma5 · Ubuntu 18.04.6 LTS (bionic) | 5.2.2-1.3ubuntu0.1+esm1 | liblzma5 5.2.2-1.3ubuntu0.1+esm1 | Apr 2, 2026 |
| liblzma5 · Ubuntu 20.04 LTS (focal) | 5.2.4-1ubuntu1.1+esm1 | liblzma5 5.2.4-1ubuntu1.1+esm1 | Apr 2, 2026 |
| liblzma5 · Ubuntu 22.04.1 LTS (jammy) | 5.2.5-2ubuntu1.1 | liblzma5 5.2.5-2ubuntu1.1 | Apr 2, 2026 |
| liblzma5 · Ubuntu 24.04.5 LTS (noble) | 5.6.1+really5.4.5-1ubuntu0.3 | liblzma5 5.6.1+really5.4.5-1ubuntu0.3 | Apr 2, 2026 |
| liblzma5 · Ubuntu 25.10 (questing) | 5.8.1-1ubuntu0.1 | liblzma5 5.8.1-1ubuntu0.1 | Apr 2, 2026 |
| xz · RHEL 10 | 5.6.2-4.el10_2.1 | RHSA-2026:64787 | Apr 2, 2026 |
| xz · RHEL 9 | 0:5.2.5-8.el9_8.1 | RHSA-2026:89749 | Oct 27, 2026 |
| xz · almalinux 10 | 1:5.6.2-4.el10_2.1 | ALSA-2026:64787 | Sep 8, 2026 |
| xz · almalinux 9 | 5.2.5-8.el9_8.1 | ALSA-2026:89749 | Nov 7, 2026 |
| xz · ol 10 | 1:5.6.2-4.el10_2.1 | ELSA-2026-64787-0 | Sep 8, 2026 |
| xz · ol 9 | 0:5.2.5-8.el9_8.1 | ELSA-2026-89749 | Nov 7, 2026 |
| xz · rocky 10 | 1:5.6.2-4.el10_2.1 | RLSA-2026:64787 | Sep 9, 2026 |
| xz · rocky 9 | 0:5.2.5-8.el9_8.1 | RLSA-2026:89749 | Nov 7, 2026 |
| xz-devel · RHEL 9 | 0:5.2.5-8.el9_8.1 | RHSA-2026:89749 | Oct 27, 2026 |
| xz-devel · almalinux 10 | 1:5.6.2-4.el10_2.1 | ALSA-2026:64787 | Sep 8, 2026 |
| xz-devel · almalinux 9 | 5.2.5-8.el9_8.1 | ALSA-2026:89749 | Nov 7, 2026 |
| xz-devel · ol 10 | 1:5.6.2-4.el10_2.1 | ELSA-2026-64787-0 | Sep 8, 2026 |
| xz-devel · ol 9 | 0:5.2.5-8.el9_8.1 | ELSA-2026-89749 | Nov 7, 2026 |
| xz-libs · RHEL 9 | 0:5.2.5-8.el9_8.1 | RHSA-2026:89749 | Oct 27, 2026 |
| xz-libs · almalinux 10 | 1:5.6.2-4.el10_2.1 | ALSA-2026:64787 | Sep 8, 2026 |
| xz-libs · almalinux 9 | 5.2.5-8.el9_8.1 | ALSA-2026:89749 | Nov 7, 2026 |
| xz-libs · ol 10 | 1:5.6.2-4.el10_2.1 | ELSA-2026-64787-0 | Sep 8, 2026 |
| xz-libs · ol 9 | 0:5.2.5-8.el9_8.1 | ELSA-2026-89749 | Nov 7, 2026 |
| xz-lzma-compat · RHEL 9 | 0:5.2.5-8.el9_8.1 | RHSA-2026:89749 | Oct 27, 2026 |
| xz-lzma-compat · almalinux 10 | 1:5.6.2-4.el10_2.1 | ALSA-2026:64787 | Sep 8, 2026 |
| xz-lzma-compat · almalinux 9 | 5.2.5-8.el9_8.1 | ALSA-2026:89749 | Nov 7, 2026 |
| xz-lzma-compat · ol 10 | 1:5.6.2-4.el10_2.1 | ELSA-2026-64787-0 | Sep 8, 2026 |
| xz-lzma-compat · ol 9 | 0:5.2.5-8.el9_8.1 | ELSA-2026-89749 | Nov 7, 2026 |
| xz-utils · Debian 12.15 (bookworm) | 5.4.1-1+deb12u1 | DEBIAN-CVE-2026-34743 | Apr 2, 2026 |
| xz-utils · Debian 13.5 (trixie) | 5.8.1-1+deb13u1 | DEBIAN-CVE-2026-34743 | Apr 2, 2026 |
| xz-utils · Debian 14 | 5.8.3-1 | DEBIAN-CVE-2026-34743 | Apr 2, 2026 |
| xz-utils · Ubuntu 18.04.6 LTS (bionic) | 5.2.2-1.3ubuntu0.1+esm1 | xz-utils 5.2.2-1.3ubuntu0.1+esm1 | Apr 2, 2026 |
| xz-utils · Ubuntu 20.04 LTS (focal) | 5.2.4-1ubuntu1.1+esm1 | xz-utils 5.2.4-1ubuntu1.1+esm1 | Apr 2, 2026 |
| xz-utils · Ubuntu 22.04.1 LTS (jammy) | 5.2.5-2ubuntu1.1 | xz-utils 5.2.5-2ubuntu1.1 | Apr 2, 2026 |
| xz-utils · Ubuntu 24.04.5 LTS (noble) | 5.6.1+really5.4.5-1ubuntu0.3 | xz-utils 5.6.1+really5.4.5-1ubuntu0.3 | Apr 2, 2026 |
| xz-utils · Ubuntu 25.10 (questing) | 5.8.1-1ubuntu0.1 | xz-utils 5.8.1-1ubuntu0.1 | Apr 2, 2026 |
| xzdec · Ubuntu 18.04.6 LTS (bionic) | 5.2.2-1.3ubuntu0.1+esm1 | xzdec 5.2.2-1.3ubuntu0.1+esm1 | Apr 2, 2026 |
| xzdec · Ubuntu 20.04 LTS (focal) | 5.2.4-1ubuntu1.1+esm1 | xzdec 5.2.4-1ubuntu1.1+esm1 | Apr 2, 2026 |
| xzdec · Ubuntu 22.04.1 LTS (jammy) | 5.2.5-2ubuntu1.1 | xzdec 5.2.5-2ubuntu1.1 | Apr 2, 2026 |
| xzdec · Ubuntu 24.04.5 LTS (noble) | 5.6.1+really5.4.5-1ubuntu0.3 | xzdec 5.6.1+really5.4.5-1ubuntu0.3 | Apr 2, 2026 |
| xzdec · Ubuntu 25.10 (questing) | 5.8.1-1ubuntu0.1 | xzdec 5.8.1-1ubuntu0.1 | Apr 2, 2026 |
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