This vulnerability arises from an incorrect bitwise shift operation on an integer field (`pz_log2_bs`) within the zisofs decompression logic of libarchive, triggered by malformed ISO9660 Rock Ridge extension data. The improper validation leads to undefined behavior, which can cause incorrect memory allocation and application crashes. Exploitation requires a remote attacker to supply a crafted ISO file to a system running Red Hat Enterprise Linux 10. The CVSS 3.1 base score is 6.5, reflecting a network attack vector, low attack complexity, no privileges required, user interaction needed, unchanged scope, no impact on confidentiality or integrity, but high impact on availability (DoS).

Successful exploitation results in denial-of-service conditions due to application crashes caused by incorrect memory allocation. There is no impact on confidentiality or integrity of the system. The attack requires user interaction to trigger processing of the malicious ISO file. No known exploits in the wild have been reported.

Patch status is not yet confirmed — check the Red Hat advisory at https://access.redhat.com/security/cve/CVE-2026-4426 for current remediation guidance. Until a patch is applied, avoid processing untrusted ISO files containing Rock Ridge extensions to mitigate risk. Monitor Red Hat communications for updates on official fixes.