Apache XMLSchema: Denial of service through cyclic schema definitions in the schema walker

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

The Apache XmlSchema walker (xmlschema-walker) doesn't detect cycles in type derivation, substitution groups, model groups or attribute groups. A malicious schema with such a cycle can make the walker recurse until the stack overflows, causing a denial of service. Users are recommended to upgrade to version 2.3.3, which fixes this issue.

Source published

29 Sep 2026 11:34:17 UTC

Source modified

29 Sep 2026 20:13:56 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

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