Critical [CVE-2026-18922] 389-ds-base: 389-ds-base: sasl plain authentication allows privilege escalation to directory manager via stale identity in cyrus sasl auxiliary property
This critical-severity Red Hat Linux advisory covers CVE-2026-18922 affecting Red Hat Directory Server 11, Red Hat Directory Server 12, Red Hat Enterprise Linux 10.
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Summary
A flaw was found in 389 Directory Server. During SASL PLAIN authentication, a stale identity carried in a Cyrus SASL auxiliary property from a prior failed bind attempt can be installed on a connection following a subsequent, unrelated successful bind, regardless of which SASL mechanism completes that second bind.
An attacker can send a SASL PLAIN bind as cn=Directory Manager with an incorrect password, then complete a SASL ANONYMOUS bind on the same connection, causing the server to grant Directory Manager authority without any valid credentials. A variant using a valid low-privileged account's own successful bind instead of an anonymous one is also possible.
This flaw is rated Critical because it allows a remote, unauthenticated attacker to gain full Directory Manager privileges over an LDAPS connection — with no valid account, no user interaction, and no non-default configuration required.
Flaw is exploitable by a remote unauthenticated attacker that fully compromises confidentiality, integrity, and availability without requiring user interaction. Red Hat severity: Critical — CVSS 9.8 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
Weakness: CWE-287.
Affected products named by the advisory: Red Hat Directory Server 11; Red Hat Directory Server 12; Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; and 9 more.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
Mitigation checklist
- Administrators can restrict nsslapd-allowed-sasl-mechanisms to only the mechanisms actually required (e.g. GSSAPI, EXTERNAL, GSS-SPNEGO), excluding PLAIN. Since the exploit chain requires the first bind attempt to be a failed SASL PLAIN bind as cn=Directory Manager, removing PLAIN from the allowed mechanism list prevents that step entirely — this blocks both the originally reported variant (valid low-privileged account) and the zero-credential SASL ANONYMOUS variant, since both depend on the same initial PLAIN bind to plant the stale identity.
Official advisory · high-confidence parse· fetched 2 hours ago·verify at source
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