CVE-2026-6794: IBM Concert Use-After-Free Vulnerability

CVE-2026-6794 Overview

IBM Concert versions 1.0.0 through 3.0.0 contain a double free vulnerability caused by incorrect memory management [CWE-415]. A local attacker with low privileges can trigger the flaw to corrupt heap memory and execute arbitrary code in the context of the affected process. The issue is tracked as CVE-2026-6794 and carries local attack vector characteristics with high impact to confidentiality, integrity, and availability.

Critical Impact
Successful exploitation allows a local, low-privileged attacker to corrupt heap memory and execute arbitrary code within the IBM Concert process context.

Affected Products

IBM Concert 1.0.0
IBM Concert 2.0.0
IBM Concert 3.0.0

Discovery Timeline

2026-09-23 - CVE-2026-6794 published to the National Vulnerability Database (NVD)
2026-09-23 - Last updated in NVD database

Technical Details for CVE-2026-6794

Vulnerability Analysis

The vulnerability is a double free condition in IBM Concert releases 1.0.0 through 3.0.0. A double free occurs when the same memory region is released to the heap allocator twice, producing an inconsistent state in the allocator's internal free lists or metadata. An attacker who influences allocation and deallocation ordering can groom the heap so that the second free places attacker-controlled data into freed chunk metadata. This primitive is commonly escalated to arbitrary write and, ultimately, arbitrary code execution in the affected process context.

Because the attack vector is local and requires low privileges without user interaction, exploitation is realistic on multi-tenant hosts, shared build systems, or any environment where an unprivileged account can interact with the IBM Concert service.

Root Cause

The root cause is incorrect memory management that permits free() to be invoked more than once on the same pointer [CWE-415]. This typically results from missing pointer nullification after release, duplicated cleanup paths across error handlers, or shared ownership of a buffer between two components that both assume responsibility for deallocation.

Attack Vector

Exploitation requires local access with low privileges. The attacker interacts with an input path that reaches the vulnerable deallocation logic, triggering the duplicated free() call. By interleaving controlled allocations between the two free operations, the attacker can reclaim the freed chunk, corrupt heap metadata, and redirect execution. IBM has not published exploit code, and there are no reports of exploitation in the wild.

Refer to the IBM Support Page for Node 7288830 for vendor technical details.

Detection Methods for CVE-2026-6794

Indicators of Compromise

Unexpected crashes or segmentation faults in IBM Concert processes, particularly with heap corruption signatures in core dumps.
Glibc runtime messages such as double free or corruption or free(): invalid pointer in service logs or journald.
New or unexpected child processes spawned by the IBM Concert service account.

Detection Strategies

Enable heap hardening diagnostics such as MALLOC_CHECK_=3 or run the process under AddressSanitizer in non-production to surface double free events.
Correlate process crashes with local login events and shell activity from non-administrative accounts on hosts running IBM Concert.
Monitor for anomalous outbound connections or file writes originating from the IBM Concert process after suspected crashes.

Monitoring Recommendations

Forward IBM Concert application logs and host auditd events to a centralized SIEM for correlation with process crash telemetry.
Alert on process integrity violations, unexpected memory allocation failures, and privilege changes tied to the Concert service account.
Track file integrity on Concert binaries and configuration files to detect post-exploitation persistence.

How to Mitigate CVE-2026-6794

Immediate Actions Required

Inventory all IBM Concert deployments and identify instances running versions 1.0.0 through 3.0.0.
Apply the fixed release referenced in the IBM security bulletin as soon as it is validated in a staging environment.
Restrict local access to hosts running IBM Concert to trusted administrative accounts only.

Patch Information

IBM has published remediation guidance on the IBM Support Page for Node 7288830. Administrators should review the bulletin for the fixed version, upgrade path, and any prerequisite components before deploying the update.

Workarounds

Limit shell and interactive access on Concert hosts using role-based access control and privileged access management.
Run IBM Concert under a dedicated, least-privileged service account to limit the blast radius of arbitrary code execution.
Enable operating system exploit mitigations such as ASLR, non-executable heap, and heap allocator hardening where supported.

bash

# Configuration example: restrict local access and verify installed IBM Concert version
sudo chmod 750 /opt/ibm/concert
sudo chown concert:concert /opt/ibm/concert
rpm -qa | grep -i concert