xmlseclibs is a PHP library that implements XML Encryption and Signatures. Prior to version 3.1.5, nodes encrypted with AES‑128‑GCM, AES‑192‑GCM, or AES‑256‑GCM do not validate the authentication tag length. The flaw allows an attacker to brute‑force an authentication tag, recover the GHASH key, and decrypt the ciphertext. It also enables forging arbitrary ciphertexts without knowledge of the encryption key, thereby compromising confidentiality of data protected by the library.

The vulnerability affects the xmlseclibs library provided by robrichards. All releases before 3.1.5 are impacted. Upgrading to version 3.1.5 or a later release mitigates the issue.

The CVSS score of 8.2 denotes high severity for confidentiality compromise. The EPSS score of less than 1% suggests that exploitation is likely uncommon in the general population. The vulnerability is not listed in the CISA KEV catalog. The CVE description does not specify an attack vector, but it is inferred that supplied crafted XML input to an application using the vulnerable library could trigger the flaw. No public exploits are documented in the provided data.