High severity · published Sep 15, 2026
CVE-2026-12666
IBM MQ Java messaging is vulnerable to XML external entity injection
8.1
CVSS
0.5%
EPSS
No
On KEV
Description
IBM MQ 9.1.0.0 through 9.1.0.37 LTS, 9.2.0.0 through 9.2.0.43 LTS, 9.3.0.0 through 9.3.0.41 LTS, 9.3.0.0 through 9.3.5.1 CD, 9.4.0.0 through 9.4.0.25 LTS, 9.4.0.0 through 9.4.5.1 CD, and 10.0.0.0 Classes for Java could allow an authenticated attacker to obtain sensitive information or cause a denial of service due to XML external entity injection in MQRFH2 header processing.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 40% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MQ
MQ · IBM
9.1.0.0 through 9.1.0.37 LTS; 9.2.0.0 through 9.2.0.43 LTS; 9.3.0.0 through 9.3.0.41 LTS; 9.3.0.0 through 9.3.5.1 CD; 9.4.0.0 through 9.4.0.25 LTS; 9.4.0.0 through 9.4.5.1 CD; +1 more · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-12666
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-12666
www.ibm.com
https://www.ibm.com/support/pages/node/7284939
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