CVE-2026-4111

DOCUMENTATION: A flaw was identified in the RAR5 archive decompression logic of the libarchive library, specifically within the archivereaddata() processing path. When a specially crafted RAR5 archive is processed, the decompression routine may enter a state where internal logic prevents forward progress. This condition results in an infinite loop that continuously consumes CPU resources. Because the archive passes checksum validation and appears structurally valid, affected applications cannot detect the issue before processing. This can allow attackers to cause persistent denial-of-service conditions in services that automatically process archives. 

            STATEMENT: The Red Hat Product Security team would likely assess the severity of this vulnerability as High because it allows remote attackers to cause a persistent denial-of-service condition using a small crafted archive file. Successful exploitation requires no authentication, no special configuration, and no user interaction in environments that automatically process uploaded archives. By repeatedly submitting malicious archives, an attacker can exhaust CPU resources or worker threads in services such as file upload systems, CI/CD pipelines, mail scanners, and content indexing services that rely on libarchive for archive extraction.

            MITIGATION: Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.