CVE-2026-4426 Red Hat CVE debrief

Who should care

System administrators and security teams responsible for systems utilizing libarchive or related components should be aware of this vulnerability. Red Hat Enterprise Linux users are particularly affected, as noted in the CVE and NVD records.

Technical summary

The CVE-2026-4426 vulnerability exists in libarchive's zisofs decompression logic. It is caused by improper validation of a field (`pz_log2_bs`) read from ISO9660 Rock Ridge extensions. A remote attacker can exploit this vulnerability by supplying a specially crafted ISO file, which can lead to incorrect memory allocation and potential application crashes, resulting in a denial-of-service (DoS) condition. The vulnerability has a CVSS score of 6.5 and is classified as Medium severity.

Defensive priority

Medium-priority defensive actions are recommended due to the potential for denial-of-service (DoS) conditions.

Recommended defensive actions

• Inventory and assess systems for exposure to libarchive and related components.
• Apply vendor patches or updates as available.
• Implement compensating controls such as monitoring for suspicious ISO file processing activities.
• Consider restricting access to untrusted sources of ISO files.
• Review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.
• Plan vendor-supported updates or mitigations through normal change control where exposure is confirmed.
• Check relevant monitoring, detection, and logs for exposed assets that need extra review.

Evidence notes

The CVE-2026-4426 flaw exists in libarchive's zisofs decompression logic due to 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, potentially leading to incorrect memory allocation and application crashes, resulting in a denial-of-service (DoS) condition. Evidence is based on official CVE and NVD records, as well as references from Red Hat.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.