Description
chain.c in back-ldap in OpenLDAP 2.4.x before 2.4.24, when a master-slave configuration with a chain overlay and ppolicy_forward_updates (aka authentication-failure forwarding) is used, allows remote authenticated users to bypass external-program authentication by sending an invalid password to a slave server.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | openldap | 2.4.25-1 | — |
| Debian 13 | openldap | 2.4.25-1 | — |
| Debian 12 | openldap | 2.4.25-1 | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 6 | compat-openldap | 2.4.19_2.3.43-15.el6_0.2 | RHSA-2011:0347 |
| RHEL 6 | openldap +4 | 2.4.19-15.el6_0.2 | RHSA-2011:0347 |
| RHEL 5 | compat-openldap | 2.3.43_2.2.29-12.el5_6.7 | RHSA-2011:0346 |
| RHEL 5 | openldap +5 | 2.3.43-12.el5_6.7 | RHSA-2011:0346 |
Advisories 2
- RHSA-2011:0347 Red Hat Security Advisory: openldap security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- RHSA-2011:0346 Red Hat Security Advisory: openldap security and bug fix update Red Hat Security Advisories (RHSA) · Nov 22, 2025
References
- GLSA-201406-36 vendor-advisory
- RHSA-2011:0346 vendor-advisory
- 1025188 vdb-entry
- 43708 third-party-advisory
- http://www.openldap.org/its/index.cgi/Software%20Bugs?id=6607
- [openldap-technical] 20100429 ppolicy master/slave issue mailing-list
- http://www.openldap.org/devel/cvsweb.cgi/servers/slapd/back-ldap/chain.c.diff?r1=1.76&r2=1.77&hideattic=1&sortbydate=0
- [openldap-announce] 20110212 OpenLDAP 2.4.24 available mailing-list
- MDVSA-2011:056 vendor-advisory
- https://bugzilla.novell.com/show_bug.cgi?id=674985
- [oss-security] 20110225 Re: CVE Request -- OpenLDAP -- two issues mailing-list
- RHSA-2011:0347 vendor-advisory
- http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10705
- MDVSA-2011:055 vendor-advisory
- 43718 third-party-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=680466
- [oss-security] 20110224 CVE Request -- OpenLDAP -- two issues mailing-list
- http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10735
- USN-1100-1 vendor-advisory
- ADV-2011-0665 vdb-entry
- 43331 third-party-advisory