Advisory · CVE-2026-6928
Use-after-free in IBM Concert risks code execution
IBM Concert 1.0.0 through 3.0.0 accesses memory after it has been freed, allowing an attacker who can influence program input to corrupt memory, crash the application, or execute arbitrary code.
- Vendor
- IBM
- Product
- IBM Concert
- Identifier / CWE
- CVE-2026-6928
CWE-416 - Action timing
- Immediate
Explain it like I’m five
The app throws away a piece of scratch paper and then keeps writing on it anyway. An attacker who gets to choose what is written on the reused paper can scribble in commands the computer will follow.
- 01Influence input
An attacker who can influence program execution or input interacts with IBM Concert 1.0.0 through 3.0.0.
- 02Premature free
The application frees a memory region while a reference to it is still live.
- 03Reuse
The attacker shapes the contents of the reallocated memory through controlled input.
- 04Exploitation
The corrupted memory is used, causing crashes or arbitrary code execution.
What happened
IBM Concert versions 1.0.0 through 3.0.0 reference or access memory after it has been freed. An attacker who can influence program execution or input may exploit this condition to corrupt memory, cause application crashes, or execute arbitrary code. IBM rates the issue critical at CVSS 9.8 in its security bulletin, which covers this flaw alongside CVE-2026-6721 and CVE-2026-6730.
What to do
- Follow the IBM security bulletin for remediation and apply it to all Concert deployments.
- Restrict access to Concert instances to trusted networks and users until remediated.
- Monitor Concert hosts for crashes or anomalous process behavior.
- Investigate repeated crashes as potential exploitation attempts.
Management note
Use-after-free flaws are often the raw material for reliable exploits once the easier injection bugs are patched. Do not treat this as the least urgent of the three Concert flaws just because exploitation takes more skill; the 9.8 rating reflects what a capable attacker can do with it.