IBM Support

Security Bulletin: Vulnerability in Diffie-Hellman ciphers affects IBM WebSphere MQ Telemetry (CVE-2015-4000)

Security Bulletin


The Logjam Attack on TLS connections using the Diffie-Hellman (DH) key exchange protocol affects IBM WebSphere MQ Telemetry (MQXR) service.

Vulnerability Details

CVEID: CVE-2015-4000
The TLS protocol could allow a remote attacker to obtain sensitive information, caused by the failure to properly convey a DHE_EXPORT ciphersuite choice. An attacker could exploit this vulnerability using man-in-the-middle techniques to force a downgrade to 512-bit export-grade cipher. Successful exploitation could allow an attacker to recover the session key as well as modify the contents of the traffic. This vulnerability is commonly referred to as "Logjam".
CVSS Base Score: 4.3
CVSS Temporal Score: See for the current score
CVSS Environmental Score*: Undefined
CVSS Vector: (AV:N/AC:M/Au:N/C:P/I:N/A:N)

Affected Products and Versions

The affected ciphersuite is available via the Telemetry (MQXR) service provided by;

  • IBM WebSphere MQ and earlier maintenance
  • IBM WebSphere MQ and earlier maintenance
  • IBM WebSphere MQ and earlier maintenance


The affected ciphersuites are disabled completely or disabled for small key sizes in the Telemetry MQXR service by default in;

  • IBM WebSphere MQ and later fix packs
  • IBM WebSphere MQ and later fix packs, in the interim apply APAR IT11660
  • IBM WebSphere MQ and later fix packs, in the interim apply APAR IT11660

Workarounds and Mitigations

The affected ciphersuites can be disabled in the Telemetry (MQXR) service by restricting the ciphersuites that are used by the Java runtime.

National Security Agency (NSA) Suite B Cryptography

The government of the Unites States of America produces technical advice on IT systems and security, including data encryption. The US National Security Agency (NSA) recommends a set of interoperable cryptographic algorithms in its Suite B standard.

The Suite B standard specifies a mode of operation in which only a specific set of secure cryptographic algorithms are used. The Suite B standard specifies:

  • The encryption algorithm (AES)
  • The key exchange algorithm (Elliptic Curve Diffie-Hellman, also known as ECDH)
  • The digital signature algorithm (Elliptic Curve Digital Signature Algorithm, also known as ECDSA)
  • The hashing algorithms (SHA-256 or SHA-384)

Configure the Telemetry (MQXR) service to only accept Suite B cryptographic algorithms by adding the following line to the file under the ../mqxr/config subdirectory of the IBM WebSphere MQ installation;

You should verify applying this configuration change does not cause any compatibility issues. If you change the default setting after applying the fix, you will expose yourself to the attack described above. IBM recommends that you review your entire environment to identify other areas where you have enabled the Diffie-Hellman key-exchange protocol used in TLS and take appropriate mitigation and remediation actions.

Get Notified about Future Security Bulletins

Important Note

IBM strongly suggests that all System z customers be subscribed to the System z Security Portal to receive the latest critical System z security and integrity service. If you are not subscribed, see the instructions on the System z Security web site. Security and integrity APARs and associated fixes will be posted to this portal. IBM suggests reviewing the CVSS scores and applying all security or integrity fixes as soon as possible to minimize any potential risk.




Reported to IBM by the WeakDH team at

Change History

4th June 2015: Original version published
19th June 2015: Details of fix added
2nd November 2015: Details of 7.1 and 7.5 ifixes added

*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.


Review the IBM security bulletin disclaimer and definitions regarding your responsibilities for assessing potential impact of security vulnerabilities to your environment.

[{"Product":{"code":"SSFKSJ","label":"WebSphere MQ"},"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Component":"WMQ Telemetry","Platform":[{"code":"PF002","label":"AIX"},{"code":"PF010","label":"HP-UX"},{"code":"PF016","label":"Linux"},{"code":"PF027","label":"Solaris"},{"code":"PF033","label":"Windows"}],"Version":"8.0;7.5;7.1","Edition":"All Editions","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
15 June 2018