The flaw in 389 Directory Server’s SMD5 password storage plugin results in an unsigned integer underflow when the plugin calculates the salt length from a crafted password hash that is shorter than 16 bytes. The underflow causes a buffer over-read, which in turn crashes the LDAP server during authentication. The consequence is a denial‑of‑service condition that prevents the directory service from responding to client requests.

Red Hat Directory Server versions 11, 12, and 13, and all Red Hat Enterprise Linux releases 6 through 10 are affected by the vulnerability.

The CVSS score is 4.9, indicating moderate severity, and the EPSS score is not available. The vulnerability is not listed in the CISA KEV catalog. An attacker can exploit the flaw by prompting the server to process a carefully crafted, short password hash during authentication, triggering a crash that results in a denial of service. The attack appears to be possible from a remote LDAP client that can send authentication requests to the vulnerable server, though it does not provide code execution or data exfiltration capabilities.