CVE-2026-4426

A flaw was found in libarchive. An Undefined Behavior vulnerability exists in the zisofs decompression logic, caused by improper validation of a field (pz_log2_bs) read from ISO9660 Rock Ridge extensions. A remote attacker can exploit this by supplying a specially crafted ISO file. This can lead to incorrect memory allocation and potential application crashes, resulting in a denial-of-service (DoS) condition.

This MODERATE impact vulnerability in libarchive's zisofs decompression logic can lead to a denial of service. The flaw is triggered when processing a specially crafted ISO9660 image containing an invalid shift exponent. Red Hat products that process untrusted ISO files using libarchive are susceptible to crashes.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, avoid processing untrusted ISO9660 images with libarchive. Restricting the sources of ISO files and ensuring they originate from trusted entities can prevent exploitation.