CVE-2026-47842: Deterministic AES/CBC Encryption in Spring Security AesBytesEncryptor Allows Ciphertext Correlation

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-26 · updated 2026-09-04
Weakness: CWE-326

Description

Applications using AesBytesEncryptor with the two-argument constructor or when passing a null IV generator and CBC as the encryption mode encrypt data with AES/CBC using a null (all-zero) initialization vector. Spring Security 7.1.0 Spring Security 7.0.0 - 7.0.6 Spring Security 6.5.0 - 6.5.11 Spring Security 6.4.0 - 6.4.18 Spring Security 5.8.0 - 5.8.27 Spring Security 5.7.0 - 5.7.25

Affected products

Spring Security: from 5.7.0 before 5.7.26; from 5.8.0 before 5.8.28; from 6.4.0 before 6.4.19; from 6.5.0 before 6.5.12; from 7.0.0 before 7.0.6.1; from 7.1.0 before 7.1.0.1 — fixed in 5.7.26, 5.8.28, 6.4.19, 6.5.12, 7.0.6.1, 7.1.0.1
Spring Security: from 7.0.0 through 7.0.6; from 6.5.0 through 6.5.11; from 6.4.0 through 6.4.18; from 5.8.0 through 5.8.27; from 5.7.0 through 5.7.25; 7.1.0

How to fix

Upgrade to a fixed version: Spring Security 5.7.26, 5.8.28, 6.4.19, 6.5.12. Check the vendor advisory for mitigations.

References

https://spring.io/security/cve-2026-47842

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