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Security Bulletin: GSKit certificate chain vulnerability in IBM Security Directory Server and Tivoli Directory Server (CVE-2013-6747)

Flash (Alert)


A vulnerability has been identified in the GSKit component utilized by IBM Security Directory Server (ISDS) and IBM Tivoli Directory Server (TDS). A malformed certificate chain can cause the ISDS or TDS client application or server process using GSKit to hang or crash. Remediation for the issue consists of upgrading affected GSKit following the instructions at the end of this bulletin.



ISDS and TDS use GSKit for SSL/TLS connections. The GSKit implementation is vulnerable to an attack from a malformed certificate chain. Were an attacker to use such a certificate when initiating an SSL/TLS connection, they could cause the ISDS or TDS client application or server process to hang or crash.
The attack does not require local network access or authentication but specialized knowledge and techniques are required. An exploit would not impact the confidentiality of information or the integrity of data, however availability of the system can be compromised.

CVSS Base Score: 7.1
CVSS Temporal Score:
CVSS Environmental Score*: Undefined
CVSS Vector: (AV:N/AC:M/Au:N/C:N/I:N/A:C)

All supported IBM Security Directory Server and Tivoli Directory Server versions are affected.


  • If using GSKit v7, upgrade to GSKit version or higher as soon as possible.
  • If using GSKit v8, upgrade to GSKit version or higher as soon as possible.

    Vendor Fix(es):
    Tivoli Directory Server Version GSKit Version Interim Fix
    Tivoli Directory Server 6.1 GSKit v7
    Tivoli Directory Server 6.2.0 GSKit v7
    Tivoli Directory Server 6.3.0 GSKit v8
    IBM Security Directory Server 6.3.1 GSKit v8

    No workaround


    · CVE-2013-6747
    · Complete CVSS Guide
    · X-Force Vulnerability Database
    · IBM Secure Engineering Web Portal
    · IBM Product Security Incident Response Blog


    24 January 2014 Initial publication

    *The CVSS Environment Score is customer environment specific and will ultimately impact the Overall CVSS Score. Customers can evaluate the impact of this vulnerability in their environments by accessing the links in the Reference section of this Flash.

    Note: According to the Forum of Incident Response and Security Teams (FIRST), the Common Vulnerability Scoring System (CVSS) is an "industry open standard designed to convey vulnerability severity and help to determine urgency and priority of response." IBM PROVIDES THE CVSS SCORES "AS IS" WITHOUT WARRANTY OF ANY KIND, INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. CUSTOMERS ARE RESPONSIBLE FOR ASSESSING THE IMPACT OF ANY ACTUAL OR POTENTIAL SECURITY VULNERABILITY.

  • Document information

    More support for: IBM Security Directory Server

    Software version: 6.1, 6.2, 6.3, 6.3.1

    Operating system(s): Platform Independent

    Reference #: 1662902

    Modified date: 24 January 2014

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