CVE-2026-95616: Apache WSS4J: Unauthenticated denial of service via integer overflow in DER parsing of X.509 certificate extensions

Apache WSS4J has an integer overflow in its DER bounds check that lets an oversized allocation pass validation. An unauthenticated attacker can send a SOAP message whose X.509 certificate SubjectKeyIdentifier extension declares a length of 0x7FFFFFFF; WSS4J decodes that extension while resolving the signature key reference, before the message is authenticated, so a tiny extension can force about a 2 GB allocation. Repeating the request exhausts server memory and denies service, with no confidentiality or integrity impact. Any service that uses a vulnerable WSS4J release to process unauthenticated SOAP with WS-Security signatures is affected. There is no known public proof of concept and the issue is not listed in CISA KEV.

Upgrade Apache WSS4J to 4.0.2, 3.0.6, or 2.4.4 (whichever release line you use) and redeploy every application that embeds it, including transitive dependencies pulled in by Apache CXF or other WS-Security stacks. Until the upgrade is in place, constrain process memory and request size for unauthenticated SOAP endpoints so a single oversized allocation cannot exhaust the host.