CVE-2026-108039: Apache CXF: Prevent unbounded XML document size in StaxUtils by adding default element and character limits

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.5% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-09 · updated 2026-10-16
Weakness: CWE-776

Description

By default, StaxUtils placed no limit on the total number of elements or the total number of characters in an XML document. A very large request could therefore use a lot of memory and CPU during parsing, especially where CXF builds a DOM from the input (for example SAAJ or WS-Security), and could cause a denial of service when no request size limit was configured. Both limits now have defaults: the maximum element count is 100 × maxChildElements (5,000,000 by default), and the maximum document size is 256M characters. Applications that process larger documents can raise the limits with the org.apache.cxf.stax.maxElementCount and org.apache.cxf.stax.maxXMLCharacters properties. Users are recommended to upgrade to versions 4.2.4 or 4.1.9 or 3.6.13, which fix this issue.

Affected products

Apache Software Foundation Apache CXF: before 3.6.13; from 4.0.0 before 4.1.9; from 4.2.0 before 4.2.4 — fixed in 3.6.13, 4.1.9, 4.2.4

How to fix

Upgrade to a fixed version: Apache Software Foundation Apache CXF 3.6.13, 4.1.9, 4.2.4. Check the vendor advisory for mitigations.

References

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