CVE-2025-5915 is a heap-based buffer overflow vulnerability identified in the libarchive library, a widely used open-source library for reading and writing streaming archive formats. The vulnerability occurs due to a flaw in handling filter blocks where the size of a filter block can exceed the Lempel-Ziv-Storer-Schieber (LZSS) compression window size. This causes the library to read beyond the allocated heap buffer, resulting in a heap buffer over-read. Such an over-read can cause unpredictable program behavior, including application crashes leading to denial of service, or potentially the disclosure of sensitive information residing in adjacent memory regions. The vulnerability affects Red Hat Enterprise Linux 10, which bundles libarchive. The CVSS 3.1 base score is 3.9, indicating low severity, with the vector AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:L. This means exploitation requires local access with low complexity, privileges, and some user interaction, and the impact is limited to confidentiality with no integrity or availability impact beyond minor denial of service. No known exploits are currently reported in the wild, and no patches have been linked yet. The vulnerability is primarily a local threat, potentially exploitable by a malicious user or process with limited privileges on the affected system.

For European organizations, the primary impact of CVE-2025-5915 is the risk of local denial of service and limited information disclosure on systems running Red Hat Enterprise Linux 10 with the vulnerable libarchive version. This could disrupt critical services if exploited, especially in environments where local user access is common or where untrusted users have some level of system interaction. The confidentiality impact, while limited, could expose sensitive data from memory, which may be critical in sectors handling sensitive information such as finance, healthcare, or government. However, the requirement for local privileges and user interaction significantly reduces the risk of remote exploitation or widespread impact. Organizations with strict access controls and minimal local user privileges will face lower risk. The absence of known exploits in the wild further reduces immediate threat levels but does not eliminate the need for vigilance.

European organizations should implement the following specific mitigations: 1) Monitor Red Hat security advisories closely for patches addressing CVE-2025-5915 and apply updates promptly once available. 2) Restrict local user access on systems running Red Hat Enterprise Linux 10 to trusted personnel only, minimizing the attack surface. 3) Employ strict privilege separation and least privilege principles to limit the ability of local users to exploit this vulnerability. 4) Use application whitelisting and endpoint protection to detect and prevent exploitation attempts. 5) Conduct regular audits of user accounts and access rights to ensure no unauthorized local access. 6) In environments where local user interaction is unavoidable, consider containerization or sandboxing of applications using libarchive to limit potential impact. 7) Implement memory protection mechanisms such as Address Space Layout Randomization (ASLR) and heap protections to reduce exploitation success likelihood. 8) Prepare incident response plans for potential denial of service or data leakage incidents related to this vulnerability.