CVE-2026-0989 identifies a vulnerability in the RelaxNG parser component of libxml2, a widely used XML parsing library integrated into Red Hat Enterprise Linux 10. The flaw stems from the parser's inadequate handling of external schema inclusions, specifically the lack of enforcement of a maximum inclusion depth when processing nested <include> directives. This can be exploited by an attacker who supplies specially crafted or excessively complex RelaxNG schemas that trigger uncontrolled recursion during parsing. The recursive calls consume stack memory, eventually leading to stack exhaustion and causing the application using the parser to crash. This crash can be leveraged to cause a denial-of-service (DoS) condition, disrupting service availability. The vulnerability does not affect confidentiality or integrity since it does not allow code execution or data manipulation, and it does not require authentication or user interaction. The CVSS 3.1 base score is 3.7, reflecting low severity due to the high attack complexity and limited impact. No public exploits have been reported, and no patches are currently linked, though Red Hat is expected to release updates. The issue is relevant primarily to systems running Red Hat Enterprise Linux 10 that utilize libxml2 for XML schema validation.

The primary impact of CVE-2026-0989 is denial-of-service through application crashes caused by stack exhaustion during XML schema parsing. Organizations relying on Red Hat Enterprise Linux 10 for critical services that process XML data with libxml2 may experience service interruptions if targeted. This can affect servers handling XML-based configuration, data exchange, or validation tasks. While the vulnerability does not compromise data confidentiality or integrity, the availability impact could disrupt business operations, especially in environments with automated XML processing or web services. The requirement for network access but high attack complexity limits widespread exploitation, reducing immediate risk. However, targeted attacks against critical infrastructure or high-value systems using vulnerable configurations could cause operational downtime and associated costs.

Organizations should monitor Red Hat security advisories for patches addressing CVE-2026-0989 and apply them promptly once available. In the interim, administrators can mitigate risk by restricting or validating XML schema inputs to prevent processing of untrusted or overly complex RelaxNG schemas. Implementing resource limits on stack size or parser recursion depth, if configurable, can reduce the risk of stack exhaustion. Employing application-level input validation and sandboxing XML parsing processes can further contain potential crashes. Network-level controls to limit exposure of services that parse RelaxNG schemas from untrusted sources are advisable. Regularly auditing systems for usage of libxml2 and updating to the latest stable versions will help maintain security posture.