The vulnerability arises because the Wss4jSecurityInterceptor in Spring Web Services sets the allowRSA15KeyTransportAlgorithm flag to true by default, which permits the use of the RSA PKCS#1 v1.5 encryption algorithm for key transport during WS-Security decryption. This algorithm is considered broken or risky (CWE-327). Unless operators explicitly disable this flag, the system accepts RSA 1.5 encrypted key material, potentially weakening cryptographic security. The issue affects multiple versions of Spring Web Services from 3.1.0 up to 5.0.1. There is no vendor advisory or patch information provided, and no known exploits in the wild have been reported.

The use of a broken or risky cryptographic algorithm (RSA PKCS#1 v1.5) for key transport in WS-Security decryption could reduce the cryptographic strength of the system, potentially allowing attackers to exploit weaknesses in the RSA 1.5 algorithm. The CVSS score of 4.8 indicates a medium severity impact with low confidentiality and integrity impact and no availability impact. However, no known exploits have been reported, and the vulnerability requires high attack complexity without privileges or user interaction.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Operators should explicitly reconfigure the allowRSA15KeyTransportAlgorithm flag to false to disable acceptance of RSA PKCS#1 v1.5 encrypted key material. Until an official fix is available, this configuration change is the recommended mitigation to avoid using the risky cryptographic algorithm.