Advisory · CVE-2026-6721
Unauthenticated OS command injection in IBM Concert
IBM Concert 1.0.0 through 3.0.0 incorporates specially crafted input into OS commands, allowing an unauthenticated remote attacker to execute arbitrary commands with the application's privileges.
- Vendor
- IBM
- Product
- IBM Concert
- Identifier / CWE
- CVE-2026-6721
CWE-78 - Action timing
- Immediate
Explain it like I’m five
The app takes words you type and pastes them straight into instructions for the computer, without checking them first. A stranger can type extra instructions that the computer obediently runs.
- 01Crafted input
An unauthenticated remote attacker submits specially crafted input to IBM Concert.
- 02Command assembly
The input is incorporated into OS commands without proper neutralization.
- 03Injection
The attacker's commands are executed by the underlying operating system.
- 04Takeover
Arbitrary command execution runs with the privileges of the affected application.
What happened
IBM Concert versions 1.0.0 through 3.0.0 allow an unauthenticated remote attacker to supply specially crafted input that is incorporated into OS commands, resulting in arbitrary command execution on the underlying system. Successful exploitation yields remote code execution with the privileges of the affected application. IBM rates the issue critical at CVSS 9.8 in its security bulletin.
What to do
- Follow the IBM security bulletin for remediation and apply it to all Concert deployments.
- Until remediated, restrict network access to Concert instances, especially from untrusted networks.
- Review application and system logs for unusual input patterns or unexpected process execution.
- Investigate any signs of post-exploitation activity on affected hosts.
Management note
Unauthenticated remote code execution at 9.8 is the highest urgency class: no credentials, no user interaction, full command execution. If Concert is internet-facing, treat this as an active incident until you can prove otherwise.