PatchTheCVECVE-2026-34743: XZ Utils provide a general-purpose data-compression library plus command-line tools
CVE-2026-34743 is a medium-severity flaw (CVSS 5.3) affecting xz. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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.
Why this priority
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 5.3 (Medium) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.5% (top 56%) |
| CISA exploited list | No |
| Weakness | CWE-122 |
| Published | 2026-04-02 |
| Last modified | 2026-07-24 |
Last updated 2026-07-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2026-34743?
xz: upgrade to 5.8.3. Exact commands for each OS are on this page.
Is CVE-2026-34743 being exploited?
CVE-2026-34743 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2026-34743 affect?
CVE-2026-34743 affects xz. Severity is medium (CVSS 5.3). 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 w
How urgent is CVE-2026-34743?
Priority 34/100. Remotely exploitable, no login, no user action