CVE-2026-12150 Overview
CVE-2026-12150 is a stack-based buffer overflow [CWE-121] in IBM MQ that affects TLS certificate processing. IBM MQ improperly validates deeply nested certificate data when handling a TLS client certificate. A remote attacker holding a trusted TLS client certificate can trigger a denial of service and potentially affect memory contents on the broker.
The flaw impacts multiple long-term support (LTS) and continuous delivery (CD) branches of IBM MQ, including the 9.1.x, 9.2.x, 9.3.x, 9.4.x, and 10.0.0.0 release lines.
Critical Impact
A remote attacker with a trusted TLS client certificate can crash IBM MQ queue managers and potentially influence process memory, disrupting enterprise messaging workloads.
Affected Products
- IBM MQ 9.1.0.0 through 9.1.0.37 LTS and 9.2.0.0 through 9.2.0.43 LTS
- IBM MQ 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, and 9.4.0.0 through 9.4.5.1 CD
- IBM MQ 10.0.0.0
Discovery Timeline
- 2026-09-15 - CVE-2026-12150 published to the National Vulnerability Database (NVD)
- 2026-09-17 - Last updated in NVD database
Technical Details for CVE-2026-12150
Vulnerability Analysis
CVE-2026-12150 exists in the TLS certificate parsing path used by IBM MQ during mutual TLS authentication. IBM MQ fails to properly validate deeply nested certificate data structures. When the queue manager parses a malformed certificate, the parsing routine writes past a fixed-size stack buffer, producing a stack-based buffer overflow classified as [CWE-121].
The overflow produces two observable outcomes. First, the affected process aborts, causing a denial of service against the queue manager. Second, adjacent stack memory can be influenced by the attacker-controlled certificate content, which may lead to confidentiality or integrity impact on process memory.
Root Cause
The root cause is missing depth and structure validation during X.509 certificate parsing. Certificates permit nested Abstract Syntax Notation One (ASN.1) structures, and IBM MQ does not bound recursion or buffer usage when traversing them. Attacker-supplied nesting drives the parser into unsafe stack writes.
Attack Vector
Exploitation requires network access to a TLS listener on the queue manager and a client certificate signed by a trusted certificate authority (CA). The attacker presents a crafted certificate chain with deeply nested fields during the TLS handshake. The handshake parser triggers the overflow before application-level authorization decisions occur. High attack complexity reflects the need for both a trusted certificate and a precisely crafted ASN.1 structure.
No public proof-of-concept exploit is available. Refer to the IBM Security Advisory for vendor-supplied technical details.
Detection Methods for CVE-2026-12150
Indicators of Compromise
- Unexpected crashes, FDC entries, or amqzxma0 process restarts on IBM MQ queue managers correlated with inbound TLS handshakes.
- TLS handshake failures from client certificates containing unusually large or deeply nested ASN.1 structures.
- Repeated connection attempts from a single trusted client identity immediately preceding a queue manager restart.
Detection Strategies
- Parse IBM MQ error logs (AMQERR01.LOG) for channel termination events and SSL/TLS errors such as MQRC_SSL_INITIALIZATION_ERROR and AMQ9633.
- Inspect TLS handshakes at the network layer for oversized client certificates or abnormal ASN.1 nesting depth using a network detection and response (NDR) sensor.
- Correlate queue manager process termination events with preceding inbound TLS sessions to identify handshake-driven crashes.
Monitoring Recommendations
- Alert on repeated queue manager restarts or FDC generation within short time windows.
- Monitor the certificate revocation list (CRL) and CA trust store for unexpected client certificates issued to non-standard identities.
- Forward IBM MQ logs and TLS metadata to a centralized SIEM for correlation across queue manager instances.
How to Mitigate CVE-2026-12150
Immediate Actions Required
- Apply the IBM-provided interim fix or upgrade to a fixed maintenance level per the IBM Security Advisory.
- Inventory all IBM MQ queue managers running affected 9.1.x, 9.2.x, 9.3.x, 9.4.x, and 10.0.0.0 versions and prioritize internet-exposed listeners.
- Audit the queue manager trust store and revoke client certificates that are no longer required for production channels.
Patch Information
IBM has published fix information in the IBM Security Advisory covering all affected LTS and CD streams. Administrators should upgrade to the corresponding fix pack or CD release identified in the advisory for each installed branch.
Workarounds
- Restrict TLS channel access using SSLPEER and CHLAUTH rules to limit which certificate distinguished names can connect.
- Terminate TLS at a hardened reverse proxy or gateway capable of validating certificate structure before traffic reaches the queue manager.
- Reduce network exposure of MQ listener ports to trusted management and application segments only.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
