Executive brief
Spring Security's AesBytesEncryptor component can use a zero-filled initialization vector (IV) when certain constructor patterns are used, weakening the encryption of stored data. This allows attackers who gain database or configuration file access to more easily decrypt sensitive information that should be protected by AES encryption.
Technical details
AesBytesEncryptor is a utility class in Spring Security used to encrypt sensitive data at rest. When instantiated with the two-argument constructor or when a null IV generator is passed with CBC mode encryption, the component defaults to using a null (all-zero) initialization vector rather than a cryptographically random one. This is a cryptographic weakness because CBC mode relies on unpredictable IVs; a fixed IV leaks patterns in encrypted data and enables precomputation attacks. An attacker with access to encrypted data and the encryption key can exploit this predictability. The vulnerability affects Spring Security versions 5.7.0 through 7.1.0. Patches are available and users should upgrade to patched releases or configure explicit random IV generators.
Affected products
- Spring Spring Security 5.7.0-5.7.25, 5.8.0-5.8.27, 6.4.0-6.4.18, 6.5.0-6.5.11, 7.0.0-7.0.6, 7.1.0
Timeline
- 2026-08-26: disclosed