Inbound WS‑Security processing in Spring Web Services exposes a cryptographic weakness: the interceptor defaults to allow the RSA PKCS#1 v1.5 key transport algorithm. This weaker algorithm is vulnerable to padding oracle and other attacks, and the default reverts to the unsafe option instead of the safer default used by Apache WSS4J. An attacker could craft a message that uses the insecure algorithm to manipulate the encrypted key material or potentially gain unauthorized access to the protected payload.

The vulnerability affects Spring Web Services versions 5.0.0 through 5.0.1, 4.1.0 through 4.1.3, 4.0.0 through 4.0.18, and 3.1.0 through 3.1.8.

The CVSS score is 4.8, indicating low overall severity. No EPSS score is available, and the vulnerability is not listed in CISA’s KEV catalog, suggesting low exploitation probability. The attack vector is network via inbound WS‑Security messages; it requires an attacker to send a crafted message that uses the RSA PKCS#1 v1.5 encrypted key. The default configuration makes exploitation easier, but the weakness is limited to systems directly accepting inbound WS‑Security traffic.