Apache WSS4J CVE-2026-95616

Requires the target to expose an Apache WSS4J-backed WS-Security/SOAP endpoint that processes signed messages and resolves X.509 key references (e.g., via Apache CXF or another SOAP stack using WSS4J for signature verification). The certificate is decoded BEFORE authentication, so no credentials are needed and no non-default configuration beyond having signature/key-reference processing enabled is required. Limiting factors: the endpoint must actually invoke WSS4J's DER parsing of certificate extensions during inbound signature handling, and impact is confined to availability (memory exhaustion) - there is no path to code execution or data disclosure. Affected only on WSS4J 4.0.0-4.0.1, 3.0.0-3.0.5, and versions before 2.4.4.

No CVSS vector, EPSS score, KEV entry, or POC is present in the provided data, so risk must be assessed from the description and Apache's 'important' severity rating. The description establishes an unauthenticated, network-reachable, low-complexity condition: an integer overflow in WSS4J's DER bounds check allows an oversized-length declaration (0x7FFFFFFF) in an X.509 SubjectKeyIdentifier extension to pass validation, and the certificate is decoded while resolving the signature's key reference BEFORE authentication - so no credentials or prior trust are needed. The impact is availability-only (memory exhaustion via repeated 2 GB allocations); there is no confidentiality or integrity loss described. This aligns with my assessed CVSS 3.1 of 7.5 (AV:N/AC:L/PR:N/UI:N/A:H). Real-world priority is moderate-to-high for exposed SOAP/WS-Security endpoints: exploitation is trivially scriptable (a single crafted SOAP message repeated), but the ceiling is DoS, not code execution. Exploitation status is 'no public exploit identified at time of analysis' - absence of EPSS/KEV/POC data means widespread active exploitation cannot be asserted. The one uncertainty to flag: NVD has not yet assigned a CVSS vector or CWE (both N/A in input), so the AV:N/PR:N assessment relies on the oss-security advisory text stating the decode occurs pre-authentication - this should be confirmed against the vendor's final NVD record.

An unauthenticated attacker sends a SOAP request to a WS-Security endpoint containing an X.509 certificate whose SubjectKeyIdentifier extension declares a length of 0x7FFFFFFF; WSS4J's flawed DER bounds check permits the oversized allocation, and an eleven-byte extension triggers a 2 GB heap allocation while the signature key reference is resolved before authentication. By repeating the request, the attacker exhausts server memory and causes denial of service. No public exploit code is identified at time of analysis, though the mechanism is simple enough to weaponize quickly.