The deref_parseCtrl function in servers/slapd/overlays/deref.c in OpenLDAP 2.4.13 through 2.4.40 allows remote attackers to cause a denial of service (NULL pointer dereference and crash) via an empty attribute list in a deref control in a search request.

slapd in OpenLDAP before 2.4.30 allows remote attackers to cause a denial of service (assertion failure and daemon exit) via an LDAP search query with attrsOnly set to true, which causes empty attributes to be returned.

libraries/libldap/tls_m.c in OpenLDAP, possibly 2.4.31 and earlier, when using the Mozilla NSS backend, always uses the default cipher suite even when TLSCipherSuite is set, which might cause OpenLDAP to use weaker ciphers than intended and make it easier for remote attackers to obtain sensitive information.

Off-by-one error in the UTF8StringNormalize function in OpenLDAP 2.4.26 and earlier allows remote attackers to cause a denial of service (slapd crash) via a zero-length string that triggers a heap-based buffer overflow, as demonstrated using an empty postalAddressAttribute value in an LDIF entry.

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.

bind.cpp in back-ndb in OpenLDAP 2.4.x before 2.4.24 does not require authentication for the root Distinguished Name (DN), which allows remote attackers to bypass intended access restrictions via an arbitrary password.

modrdn.c in slapd in OpenLDAP 2.4.x before 2.4.24 allows remote attackers to cause a denial of service (daemon crash) via a relative Distinguished Name (DN) modification request (aka MODRDN operation) that contains an empty value for the OldDN field.

The slap_modrdn2mods function in modrdn.c in OpenLDAP 2.4.22 does not check the return value of a call to the smr_normalize function, which allows remote attackers to cause a denial of service (segmentation fault) and possibly execute arbitrary code via a modrdn call with an RDN string containing invalid UTF-8 sequences, which triggers a free of an invalid, uninitialized pointer in the slap_mods_free function, as demonstrated using the Codenomicon LDAPv3 test suite.

OpenLDAP 2.4.22 allows remote attackers to cause a denial of service (crash) via a modrdn call with a zero-length RDN destination string, which is not properly handled by the smr_normalize function and triggers a NULL pointer dereference in the IA5StringNormalize function in schema_init.c, as demonstrated using the Codenomicon LDAPv3 test suite.

libraries/libldap/tls_o.c in OpenLDAP 2.2 and 2.4, and possibly other versions, when OpenSSL is used, does not properly handle a '\0' character in a domain name in the subject's Common Name (CN) field of an X.509 certificate, which allows man-in-the-middle attackers to spoof arbitrary SSL servers via a crafted certificate issued by a legitimate Certification Authority, a related issue to CVE-2009-2408.