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CVE-2026-6730: Ibm Concert Classic Buffer Overflow (CVSS 9.8)

CVE-2026-6730 is a critical severity classic buffer overflow in Ibm Concert with a CVSS score of 9.8. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Last updated: Sep 28, 2026

Quick answer

Direct answer

CVE-2026-6730 is a critical severity classic buffer overflow in Ibm Concert with a CVSS score of 9.8. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Risk scores

CVSS base score
9.8CRITICAL
EPSS probability
0.30%
Higher than 22 percent of all CVEs
CISA KEV
Not listed
CVSS metricWhat it means
Attack vector (AV:N)Network: reachable remotely
Attack complexity (AC:L)Low complexity
Privileges required (PR:N)No privileges required
User interaction (UI:N)No user interaction
Scope (S:U)Scope unchanged
Confidentiality (C:H)High confidentiality impact
Integrity (I:H)High integrity impact
Availability (A:H)High availability impact

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

About Ibm Concert

CVE-2026-6730 affects Ibm Concert, a product from Ibm. Before acting, confirm where Ibm Concert runs in your estate, who owns it and whether it is reachable from the internet, because exposure decides real risk more than the score alone.

What the flaw is

In plain terms: IBM Concert 1.0.0 through 3.0.0 is vulnerable to a buffer overflow, caused by improper bounds checking. A local user could overflow the buffer and execute arbitrary code on the system.

The weakness class is Classic Buffer Overflow. Data is copied into a buffer without checking its size.

Based on its CVSS vector, the flaw can be reached over the network, needs no login, and needs no user interaction. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

Affected versions and timeline

FieldDetail
ProductIbm Concert
Affected versionsConcert from 1.0.0 up to and including 3.0.0
PublishedSep 23, 2026
Last modifiedSep 28, 2026
Added to CISA KEVNot listed
Assigning CNApsirt@us.ibm.com

How to detect it

  • Inventory every instance of Ibm Concert and record the running version against the affected range above.
  • Check external attack surface scans for internet facing instances of the component.
  • Review logs on affected systems for unusual requests, errors or new processes around the vulnerable function.
  • Confirm with an authenticated vulnerability scan once your scanner has a check for this CVE.

How to fix it

  • Apply the fixed version of Ibm Concert named in the vendor advisory.
  • If patching must wait, restrict network access to the affected service and put it behind authentication or a web application firewall rule.
  • Rescan after the change to prove the exposure is gone, then close the ticket.

CTEM action plan

CTEM stageWhat to do for this CVE
ScopeAdd every business service that depends on Ibm Concert to the current CTEM cycle.
DiscoverFind all instances, including shadow and cloud deployments, and record versions and exposure.
PrioritizeRank using EPSS and CVSS together with asset exposure and business impact.
ValidateConfirm the flaw is reachable and exploitable in your environment and that compensating controls work.
MobilizeAssign the fix to the asset owner with a due date matched to the priority, then verify closure.

CWE References

Technical References

Frequently asked questions

CVE-2026-6730 is a critical severity classic buffer overflow in Ibm Concert with a CVSS score of 9.8. Apply the vendor fix and confirm exposure on internet facing and business critical assets first.

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