This vulnerability arises from WildFly Elytron's password hashing and verification process that normalizes input using Unicode NFKC normalization. This normalization collapses fullwidth Unicode characters to their ASCII equivalents, effectively reducing the complexity of passwords that include such characters. As a result, an attacker can use an ASCII-only dictionary to guess passwords that were intended to be more complex due to the inclusion of non-ASCII characters. The vulnerability affects Red Hat products shipping the org.wildfly.security:wildfly-elytron-password-impl component. The issue has a high impact on confidentiality and integrity but does not affect availability. Red Hat has not provided an official fix or patch, citing challenges in ease of use, deployment, and applicability. The vulnerability is documented under CWE-173 (Improper Handling of Alternate Encoding).

Successful exploitation can lead to unauthorized access by reducing the effective password keyspace for accounts using fullwidth or other NFKC-compatible characters in their passwords. This makes password guessing attacks more feasible against affected accounts. The impact is high on confidentiality and integrity, as attackers may bypass authentication controls. There is no impact on availability. The vulnerability depends on the presence of affected password hashing implementations and the use of vulnerable password characters.

Currently, there is no official fix or patch available from Red Hat for this vulnerability. Red Hat states that available mitigation options do not meet their criteria for ease of use, deployment, applicability, or stability. Users should monitor the Red Hat advisory for updates and consider avoiding the use of fullwidth or NFKC-compatibility characters in passwords as a temporary precaution. Customers with Red Hat Technical Account Managers (TAM) can consult them for tailored guidance. Upgrading to a fixed version, if and when released, is recommended once available.