The vulnerability CVE-2026-4111 affects the RAR5 decompression logic in the libarchive library, specifically within the archive_read_data() function. When processing a maliciously crafted RAR5 archive, the decompression code can enter an infinite loop due to internal logic that prevents forward progress. Because the archive passes checksum validation and appears structurally valid, affected applications cannot detect the problem prior to processing. This results in a denial-of-service condition by consuming CPU resources indefinitely. The issue impacts Red Hat Enterprise Linux 10 and Red Hat OpenShift Container Platform 4.19. Red Hat has issued security advisories (RHSA-2026:10065 and RHSA-2026:10081) that include fixes for this vulnerability. Users of affected products are advised to apply the updates provided in these advisories to mitigate the risk.

This vulnerability can cause a denial-of-service (DoS) condition by triggering an infinite loop in the RAR5 decompression routine of libarchive, leading to continuous CPU consumption. There is no impact on confidentiality or integrity. The denial-of-service can affect any service or application that automatically processes RAR5 archives using the vulnerable libarchive version, potentially causing service disruption.

Red Hat has released official security updates that fix this vulnerability. Users of Red Hat Enterprise Linux 10 and Red Hat OpenShift Container Platform 4.19 should apply the updates as soon as they are available via the appropriate release channels. For OpenShift Container Platform 4.19, users should upgrade to version 4.19.29 or later, following Red Hat's documented upgrade procedures. No other mitigations are indicated or required beyond applying these official fixes.