CVE-2025-6021 is a high-severity stack-based buffer overflow vulnerability identified in the libxml2 library, specifically within the xmlBuildQName function. The root cause is integer overflow during buffer size calculations, which leads to an incorrect allocation size and subsequently a stack-based buffer overflow when processing specially crafted XML input. This vulnerability can cause memory corruption or denial of service (DoS) conditions. The flaw exists in Red Hat Enterprise Linux 10, which includes libxml2 as a core XML parsing library. Exploitation requires no privileges or user interaction and can be triggered remotely by supplying malicious XML data to an application that uses libxml2 for XML processing. Although no known exploits are currently in the wild, the vulnerability’s nature and ease of exploitation make it a significant risk. The CVSS v3.1 score of 7.5 reflects its high severity, with network attack vector, low attack complexity, no privileges required, no user interaction, and impact limited to availability (denial of service). There is no direct impact on confidentiality or integrity reported, but memory corruption could potentially be leveraged for further exploitation in some contexts. The vulnerability affects all versions of Red Hat Enterprise Linux 10 that include the vulnerable libxml2 version, and potentially other Linux distributions using the same libxml2 version, though this analysis focuses on Red Hat Enterprise Linux 10 as specified.

For European organizations, this vulnerability poses a significant risk to systems running Red Hat Enterprise Linux 10, which is widely used in enterprise environments across Europe for servers, cloud infrastructure, and critical applications. Exploitation could lead to denial of service, causing application crashes or system instability, which can disrupt business operations, especially for services relying on XML processing such as web services, middleware, and configuration management. While no direct confidentiality or integrity impact is confirmed, the memory corruption aspect could be a stepping stone for attackers to execute arbitrary code or escalate privileges in complex attack chains, increasing the threat level. Organizations in sectors such as finance, telecommunications, government, and critical infrastructure that rely on Red Hat Enterprise Linux 10 should be particularly vigilant. The lack of required authentication or user interaction means attackers can exploit this remotely, increasing the attack surface and risk of automated attacks or wormable scenarios if weaponized. The absence of known exploits in the wild currently provides a window for proactive mitigation before active exploitation occurs.

European organizations should immediately identify and inventory all systems running Red Hat Enterprise Linux 10 with the vulnerable libxml2 version. Since no patch links are provided in the source, organizations should monitor Red Hat’s official security advisories and promptly apply any released patches or updates addressing CVE-2025-6021. In the interim, consider mitigating exposure by restricting network access to services that process untrusted XML input, implementing strict input validation and sanitization on XML data, and employing application-layer firewalls or intrusion prevention systems with signatures targeting malformed XML payloads. Additionally, enable and review system and application logs for unusual crashes or memory errors related to XML processing. For critical systems, consider isolating or sandboxing XML processing components to limit potential impact. Regularly update and test incident response plans to handle potential denial of service or exploitation attempts. Engage with Red Hat support for guidance and potential workarounds if patches are delayed.