A flaw was found in libarchive. (CVE-2026-17591)

CVE-2026-17591 is a use-after-free vulnerability in libarchive, specifically in the archive_entry_copy_mac_metadata() function. The flaw occurs when the function deallocates an internal buffer prematurely during a data copy operation. An attacker able to provide input to an application using this function can trigger a crash (Denial of Service) or read uninitialized memory, potentially causing limited information disclosure. The vulnerability has a CVSS 3.1 base score of 3.6 (low severity) with local attack vector, high attack complexity, no privileges required, and requires user interaction. Red Hat has issued a security advisory (RHSA-2026:77775) providing updated libarchive packages to fix this issue in their Hardened Images RPMs.

The vulnerability can cause a Denial of Service by crashing applications that use the vulnerable function. Additionally, it may allow limited information disclosure by reading uninitialized memory. The CVSS score of 3.6 reflects a low severity impact with limited confidentiality impact and no integrity impact. There are no known exploits in the wild at this time.

A security update is available from Red Hat as detailed in advisory RHSA-2026:77775. Users of Red Hat Hardened Images should apply the updated libarchive packages (version 3.8.9-2.1.hum1) to remediate this vulnerability. No other mitigation steps are indicated by the vendor advisory.