CVE-2026-0989

A flaw was identified in the RelaxNG parser of libxml2 related to how external schema inclusions are handled. The parser does not enforce a limit on inclusion depth when resolving nested <include> directives. Specially crafted or overly complex schemas can cause excessive recursion during parsing. This may lead to stack exhaustion and application crashes, creating a denial-of-service risk.

This vulnerability is rated Low for Red Hat products. The flaw in libxml2's RelaxNG include handling requires attacker-controlled schema input to trigger unbounded recursion, leading to a denial of service. Exploitation is limited to scenarios where applications process untrusted RelaxNG schema files.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, restrict applications using libxml2 from processing untrusted RelaxNG schema files. Implement strict input validation and sanitization for all RelaxNG schema inputs to prevent the parsing of maliciously crafted, deeply nested include directives.