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Security Bulletin: Multiple vulnerabilities in IBM Java Runtime affect Rational Directory Server (Tivoli) & Rational Directory Administrator

Security Bulletin


There are multiple vulnerabilities in IBM® Runtime Environment Java™ Version 7 and Version 8 used by Rational Directory Server (Tivoli) and Rational Directory Administrator. These issues were disclosed as part of the IBM Java SDK updates in February 2021. Upgrade the JRE in order to resolve these issues.

Vulnerability Details

CVEID:   CVE-2020-27221
DESCRIPTION:   Eclipse OpenJ9 is vulnerable to a stack-based buffer overflow when the virtual machine or JNI natives are converting from UTF-8 characters to platform encoding. By sending an overly long string, a remote attacker could overflow a buffer and execute arbitrary code on the system or cause the application to crash.
CVSS Base score: 9.8
CVSS Temporal Score: See: for the current score.
CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)

Affected Products and Versions

Affected Product(s) Version(s)
RDS        5.2.1 iFix 13 and earlier

       1.  iFix 06 and earlier



1. Download one of the following IBM JRE versions that contain the fixes for these vulnerabilities:
        Note : For Rational Directory Administrator-, download JRE 8.x or later.
2. After downloading a fixed IBM JRE version, refer the following technote for JRE upgrade instructions:    
To improve the robustness of LDAPS (secure LDAP over TLS) connections, endpoint identification algorithms have been enabled by default. There may be situations where some applications that were previously able to successfully connect to an LDAPS server may no longer be able to do so.
With this LDAP update, LDAP is asking JSSE to validate the LDAP server's certificate to ensure it is compliant with hostname verification.  With this change, if the server's certificate is not compliant, then exception will be thrown.  In the past, LDAP did not request JSSE to perform hostname verification and a non-compliant server certificate would not have had caused an issue.
In order to resolve the issue, Regenerate the RDS server certificate(tdsserverkey.kdb) so that the certificate's subject name or certificate's subject alternate name matches the RDS server hostname, by following instructions from technote:
How can I generate my own 'tdsserverkey.kdb' keystore for TLSv12 communication and use it in a IBM Rational Directory Server (Tivoli) deployment?
After regenerating the RDS Server certificate matching with the RDS Server Hostname, use FQDN's wherever applicable.
E.g. : RDA Login Screen, Creating RDS Partition and DOORS to RDS Connection.
(If you have already regenerated the RDS Server certificate by following above technote, while upgrading to IBM JRE versions or later or or later, then no need to follow the technote again)

For versions of Rational Directory Server that are earlier than version 5.2.1, and Rational Directory Administrator versions earlier than, IBM recommends upgrading to a fixed, supported version/release/platform of the product.

If you run your own Java code using the IBM Java Runtime delivered with this product, you should evaluate your code to determine whether additional Java vulnerabilities are applicable to your code. For a complete list of vulnerabilities, refer to the "IBM Java SDK Security Bulletin", located in the References section for more information.

Workarounds and Mitigations


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Change History

29 Apr 2021: 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 Security Bulletin.


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 Location


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Document Information

Modified date:
29 April 2021