OpenBSD ldapd: Authentication result mix-up allows identity bypass in Bind
Summary
The LDAP daemon ldapd in OpenBSD 7.8 before errata 057 and 7.9 before errata 021 matches delegated BSD authentication results to connections only by file descriptor and message ID. After a connection closes, a new connection reusing the same descriptor and message ID can receive the earlier result, so a reachable attacker may complete a Bind as another identity. A missing connection can also cause a NULL pointer dereference, which may lead to a crash. ldapd is not enabled by default.
Affected
- OpenBSD 7.8 before errata 057
- OpenBSD 7.9 before errata 021
Fixed in
- OpenBSD 7.8: errata 057 (14 Sep 2026)
- OpenBSD 7.9: errata 021 (14 Sep 2026)
- Apply the latest errata for your branch; binary updates for amd64, arm64 and i386 are available via syspatch
Workaround
- Disable ldapd if it is not strictly required (it is off by default)
- Restrict network access to ldapd to known clients until patching is complete
Exploitation
- No active exploitation reported.
- No public proof of concept found.
- CISA SSVC: exploitation none, automatable no, technical impact total.
- Not listed in CISA KEV at time of research.
Our recommendation
- Check whether any OpenBSD host runs ldapd.
- If it runs, apply errata 057 (7.8) or 021 (7.9), or later errata, using syspatch on supported platforms.
- If ldapd is not needed, disable it.
- Restrict network reach of ldapd to trusted clients and monitor for unexpected Bind activity.
Public exploits
PoC-in-GitHub, Metasploit and Exploit-DB list nothing for this CVE.
Research sources
- OpenBSD Errata 7.8 www.openbsd.org
- OpenBSD Errata 7.9 www.openbsd.org
- OpenBSD 7.9 errata 021 signed patch (ldapd) ftp.openbsd.org
- Upstream commit openbsd/src (ldapd connection IDs) github.com
- OSV entry CVE-2026-103547 osv.dev
- VulDB CVE-2026-103547 vuldb.com
Researched and written up in English and German by an AI (Claude by Anthropic) based on NVD, CISA, EPSS and the sources listed. The vendor information is authoritative. Researched on 31 Oct 2026, 05:02.
Original description (NVD)
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.)
Sources
The tracker combines official, freely usable data sources – updated continuously:
- NVD (NIST) – CVEs, rating (CVSS), affected products
- CISA KEV – vulnerabilities confirmed by CISA as actively exploited
- CISA Vulnrichment – CISA assessment (SSVC) in the official CVE record
- FIRST EPSS – probability of exploitation
- Microsoft MSRC – Patch Tuesday: vulnerabilities, severity, updates
- PoC-in-GitHub – public proof-of-concept repositories
- Metasploit (Rapid7) – modules of the Metasploit Framework
- Exploit-DB (OffSec) – archive of public exploits (links only)
- Patch days: official vendor pages (linked per vendor) (Vendor patch days)
This product uses data from the NVD API but is not endorsed or certified by the NVD. EPSS data © FIRST.org.
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