How severe is CVE-2026-6721?

CVE-2026-6721 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-6721 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-6721?

CVE-2026-6721 affects Ibm Concert. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-6721?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2026-6721 published?

CVE-2026-6721 was published on 2026-09-23 and last updated on 2026-09-28.

CVE-2026-6721

CVE-2026-6721 is a critical-severity vulnerability in Ibm Concert with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-78.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 1% (72nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-78
Affected product: Ibm Concert
Published: 2026-09-23
Last modified: 2026-09-28

Description

IBM Concert 1.0.0 through 3.0.0 allows an unauthenticated remote attacker can supply specially crafted input that is incorporated into OS commands, resulting in arbitrary command execution on the underlying system. Successful exploitation allows remote code execution with the privileges of the affected application.

Frequently asked questions

What is CVE-2026-6721?: IBM Concert 1.0.0 through 3.0.0 allows an unauthenticated remote attacker can supply specially crafted input that is incorporated into OS commands, resulting in arbitrary command execution on the underlying system. Successful exploitation allows remote code execution with the privileges of the affected application.
How severe is CVE-2026-6721?: CVE-2026-6721 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-6721 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (72nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-6721?: CVE-2026-6721 affects Ibm Concert. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-6721?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-6721 published?: CVE-2026-6721 was published on 2026-09-23 and last updated on 2026-09-28.

References

https://www.ibm.com/support/pages/node/7288830

Affected products (1)

cpe:2.3:a:ibm:concert:*:*:*:*:*:*:*:*

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CVE-2026-6730 — Critical (CVSS 9.8): IBM Concert 1.0.0 through 3.0.0 is vulnerable to a buffer overflow, caused by improper bounds checking. A local user…
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CVE-2025-33015 — High (CVSS 8.8): IBM Concert 1.0.0 through 2.1.0 is vulnerable to malicious file upload by not validating the content of the file…
CVE-2026-6935 — High (CVSS 7.8): IBM Concert 1.0.0 through 3.0.0 invokes operating system commands without fully qualifying executable paths or…
CVE-2026-6794 — High (CVSS 7.8): IBM Concert 1.0.0 through 3.0.0 has a double free vulnerability that exists due to incorrect memory management. A local…

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