Public Vulnerability Reports

IBM Lotus Domino Server LDAP DoS Vulnerability



IBM Lotus Domino Server software provides messaging, calendaring and
scheduling capabilities on a variety of operating systems. More
information about the product is available from:


Remote exploitation of a denial of service vulnerability in IBM Corp.'s
Lotus Domino LDAP server allows attackers to crash the service, thereby
preventing legitimate access. iDEFENSE is currently unaware of exploits
for this vulnerability other than those maintained by iDEFENSE Labs.
Vendor patches for this iDEFENSE exclusive report are currently
unavailable. A workaround has been provided.

The problem specifically exists within the LDAP server "nldap.exe." When
sending a specially crafted bind request with a long string to the LDAP
server port (389), a NULL pointer dereference occurs, resulting in a
crash of the process.


Exploitation of this vulnerability allows unauthenticated remote
attackers to crash the LDAP service, thereby preventing legitimate
usage. This attack takes little resources to launch and can be repeated
to ensure that an unpatched computer is unable to recover even after the
administrator manually restarts the service.


iDEFENSE has confirmed the existence of this vulnerability in Lotus
Domino Server version 6.5.4. It is suspected that earlier versions of
Lotus Domino Server are also affected.


Employ firewalls, access control lists or other TCP/UDP restriction
mechanisms to limit access to systems and services. More specifically,
limit access to TCP port 389 on the LDAP server to only allow trusted
hosts to connect.


The vendor has addressed this issue in the following products:

 - IBM Lotus Notes/Domino 6.5.4 FP2
 - IBM Lotus Notes/Domino 6.5.5
 - IBM Lotus Notes/Domino 7.0.1
The vendor has published the following technote which details patching


The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-2712 to this issue. This is a candidate for inclusion in
the CVE list (, which standardizes names for
security problems.


08/23/2005   Initial vendor notification
08/23/2005   Initial vendor response
02/10/2006   Coordinated public disclosure


Sebastian Apelt is credited with the discovery of this vulnerability.

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Copyright © 2006 Verisign, Inc.

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