CVE-2026-34743 XZ Utils: Buffer overflow in lzma_index_append()
A buffer overflow in XZ Utils allows attackers to execute arbitrary code or cause denial of service via crafted compressed data.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-34743?
CVE-2026-34743 is a low-severity memory corruption vulnerability in tukaani-project xz, published on 2 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-122
Which versions are affected by CVE-2026-34743?
It affects 1 product.
Linux distribution packages (24)
xz AlmaLinux:10 | All versions | 1:5.6.2-4.el10_2.1 |
xz-devel AlmaLinux:10 | All versions | 1:5.6.2-4.el10_2.1 |
xz-libs AlmaLinux:10 | All versions | 1:5.6.2-4.el10_2.1 |
xz-lzma-compat AlmaLinux:10 | All versions | 1:5.6.2-4.el10_2.1 |
xz AlmaLinux:9 | All versions | 5.2.5-8.el9_8.1 |
xz-devel AlmaLinux:9 | All versions | 5.2.5-8.el9_8.1 |
xz-libs AlmaLinux:9 | All versions | 5.2.5-8.el9_8.1 |
xz-lzma-compat AlmaLinux:9 | All versions | 5.2.5-8.el9_8.1 |
xz Red Hat:enterprise_linux:10.2 | All versions | 1:5.6.2-4.el10_2.1 |
xz-debuginfo Red Hat:enterprise_linux:10.2 | All versions | 1:5.6.2-4.el10_2.1 |
xz-debugsource Red Hat:enterprise_linux:10.2 | All versions | 1:5.6.2-4.el10_2.1 |
xz-devel Red Hat:enterprise_linux:10.2 | All versions | 1:5.6.2-4.el10_2.1 |
xz-libs Red Hat:enterprise_linux:10.2 | All versions | 1:5.6.2-4.el10_2.1 |
xz-libs-debuginfo Red Hat:enterprise_linux:10.2 | All versions | 1:5.6.2-4.el10_2.1 |
xz-lzma-compat Red Hat:enterprise_linux:10.2 | All versions | 1:5.6.2-4.el10_2.1 |
xz-lzma-compat-debuginfo Red Hat:enterprise_linux:10.2 | All versions | 1:5.6.2-4.el10_2.1 |
xz Red Hat:hummingbird:1 | All versions | 0:5.8.3-1.1.hum1 |
xz-devel Red Hat:hummingbird:1 | All versions | 0:5.8.3-1.1.hum1 |
xz-libs Red Hat:hummingbird:1 | All versions | 0:5.8.3-1.1.hum1 |
xz-lzma-compat Red Hat:hummingbird:1 | All versions | 0:5.8.3-1.1.hum1 |
xz-static Red Hat:hummingbird:1 | All versions | 0:5.8.3-1.1.hum1 |
xz Rocky Linux:10 | All versions | 1:5.6.2-4.el10_2.1 |
xz Rocky Linux:9 | All versions | 0:5.2.5-8.el9_8.1 |
xz openSUSE:Tumbleweed | All versions | 5.8.3-1.1 |
Products include Tukaani Xz.
How do I fix CVE-2026-34743?
Upgrade to a fixed version.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-34743 being exploited?
There is no known exploitation of CVE-2026-34743 in the wild and no public exploit code.
Other vulnerabilities in tukaani-project xz
Sources
Also known as ALPINE-CVE-2026-34743, ALSA-2026:64787, ALSA-2026:89749, AZL-81800, AZL-81905, AZL-81908 and 25 more.