The Apache Tomcat EncryptInterceptor is susceptible to a padding oracle attack when enabled by default. This flaw permits an attacker to submit specially crafted ciphertext and, by observing decryption failures or error responses, recover the original plaintext of encrypted data. The disclosure could include confidential configuration information or session data stored by a web application. CWE‑1240, CWE‑209 and CWE‑642 are associated with the weakness.

The vulnerability covers Apache Tomcat versions 11.0.0‑M1 through 11.0.18, 10.0.0‑M1 through 10.1.52, 9.0.13 through 9.0.115, 8.5.38 through 8.5.100, and 7.0.100 through 7.0.109. Users are advised to upgrade to 11.0.19, 10.1.53 or 9.0.116 where the issue is fixed. No fixed releases are listed for the 8.5.x or 7.x series; administrators should seek newer releases or disable the interceptor if it is unnecessary.

The CVSS base score of 7.5 classifies the vulnerability as high severity, while an EPSS score of 13% indicates a moderate probability of exploitation in the wild. The vulnerability is not listed in the CISA KEV catalog. The likely attack vector is remote HTTP access to a Tomcat instance that has the EncryptInterceptor enabled by default; an attacker would send crafted ciphertext and analyze error responses or timing to incrementally recover plaintext.