CVE-2025-5916 is a vulnerability identified in the libarchive library, a widely used open-source library for reading and writing various archive formats. The flaw is an integer overflow or wraparound triggered when processing a Web Archive (WARC) file that claims to contain more than INT64_MAX - 4 content bytes. Specifically, the integer overflow occurs because the library does not properly validate or handle extremely large content size values, leading to arithmetic wraparound. This can cause the program to miscalculate buffer sizes or memory allocations, resulting in memory corruption or unpredictable behavior. Potential consequences include denial-of-service (application crashes or hangs) or, in some cases, memory corruption that could be leveraged for further exploitation. The vulnerability affects libarchive versions prior to 3.8.0 and is present in Red Hat Enterprise Linux 10's shipped libarchive package. Exploitation requires local privileges and user interaction, such as a user opening or processing a crafted WARC file. The CVSS 3.1 score is 3.9 (low severity), reflecting limited impact and exploitation complexity. No public exploits are known at this time. Given libarchive's role in many Linux distributions and applications that handle archives, this vulnerability could impact software that processes WARC files, including web archiving tools and forensic utilities.

For European organizations, the primary impact is the risk of denial-of-service or application instability in systems that process WARC files using vulnerable libarchive versions. This could disrupt services relying on archive processing, such as digital preservation, web archiving, or forensic analysis tools. Memory corruption could theoretically lead to further compromise, but given the low CVSS score and requirement for local privileges and user interaction, the risk of remote code execution or large-scale breaches is low. However, organizations with critical infrastructure or sensitive data that rely on libarchive should consider the potential for service interruptions or targeted attacks exploiting this flaw. The impact is more operational than confidentiality-related, but availability and integrity of archive processing could be affected. Unpatched systems may be vulnerable to crafted archives delivered via email attachments, downloads, or insider threats.

The most effective mitigation is to upgrade libarchive to version 3.8.0 or later, where this integer overflow has been fixed. Organizations should verify the libarchive version on all systems that process archives, especially those handling WARC files, and apply vendor patches promptly. Additionally, implement strict input validation and sandboxing for applications that process untrusted archive files to limit the impact of malformed inputs. Restrict user permissions to prevent unprivileged users from processing potentially malicious archives without oversight. Employ application whitelisting and endpoint protection to detect anomalous behavior during archive processing. Network-level controls can help by blocking or scanning archive files from untrusted sources before they reach end-user systems. Regularly audit and monitor logs for crashes or unusual activity related to archive handling. Finally, educate users about the risks of opening untrusted archive files, especially WARC files from unknown sources.