A stack buffer overflow occurs in the checkPrefix() function of 389 Directory Server when it copies an attacker‑controlled algorithm ID into a 256‑byte stack buffer with no bounds checking. An attacker who possesses Directory Manager privileges can store a crafted credential containing an oversized algorithm ID, causing the LDAP server to crash. The vulnerability is classified as CWE‑121 "Stack-based Buffer Overflow," and its effect is limited to denial of service; it does not allow arbitrary code execution or data disclosure.

The flaw impacts Red Hat Directory Server versions 11, 12 and 13, as well as Red Hat Enterprise Linux releases 10, 6, 7, 8 and 9. No patch or upgrade level is listed in the CVE entry, so the affected instances remain vulnerable until an official fix is deployed.

The CVSS score of 4.9 indicates a low‑to‑moderate severity. EPSS data is not available, and the vulnerability is not listed in the CISA KEV catalog, suggesting that while the problem is known, it has not yet been widely exploited in the wild. Effective exploitation requires high‑privilege Directory Manager access, so the threat is largely confined to insiders or compromised privileged accounts. Without a patch, the only mitigation is to restrict or monitor Directory Manager privileges; even then, repeated attempts could trigger service downtime.