CVE-2026-103547: Null Pointer Dereference
In ldapd in OpenBSD 7.8 before errata 057 and 7.9 before errata 021, delegated BSD authentication results are correlated only by the LDAP child process client file descriptor and LDAP message ID. After a connection closes, a later connection that reuses the same file descriptor and message ID can receive the earlier authentication result. A remote attacker who can reach ldapd can complete a Bind as another identity. A missing connection can also cause a NULL pointer dereference. (ldapd is not enabled by default.)
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
OpenBSD ldapdto a version that resolves this vulnerability.Patch errata 057 - Upgrade
Upgrade
OpenBSD ldapdto a version that resolves this vulnerability.Patch errata 021
Event History
Frequently Asked Questions
Which systems are exposed to remote authentication impersonation?
Systems running ldapd on OpenBSD 7.8 without errata 057 or OpenBSD 7.9 without errata 021 are exposed if ldapd is reachable by a remote attacker. ldapd is not enabled by default.
What does an attacker need to exploit the authentication issue?
The attacker needs network reachability to ldapd. No prior privileges or user interaction are required, but exploitation has high attack complexity because a closed connection must be followed by another connection that reuses both the LDAP child process client file descriptor and LDAP message ID.
What is the impact of successful exploitation?
An attacker can complete an LDAP Bind as another identity by receiving an earlier delegated BSD authentication result. A missing connection can also trigger a NULL pointer dereference.
How can this be remediated?
Apply errata 057 for OpenBSD 7.8 or errata 021 for OpenBSD 7.9. If patching cannot occur immediately, disable ldapd or restrict network access to it so remote attackers cannot reach the service.