CVE-2026-6730: IBM Concert 1.0.0 through 3.0.0 is vulnerable to a buffer overflow, caused by improper bounds checking

This month

CRITICAL 9.8REMOTEUPGRADE

CVE-2026-6730 is a critical-severity flaw (CVSS 9.8) affecting concert. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 76%)
CISA exploited list	No
Weakness	CWE-120
Published	2026-09-23
Last modified	2026-09-28

Publisher (CNA): IBM Corporation · Vendor: ibm

Last updated 2026-09-28 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-23 21:17 UTCPublished CVE record published
2026-09-28 20:47 UTCUpdated Record last modified

ibm concert UPGRADE

Affected: >= 1.0.0 and <= 3.0.0

Fixed in: newer than 3.0.0

Safe to downgrade to: a release before 1.0.0

1. Check installed version

apt-cache policy concert || rpm -q concert || concert --version

2. UPGRADE to newer than 3.0.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade concert

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade concert

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.0.0 (Debian / Ubuntu)

apt-cache madison concert sudo apt install concert=<VERSION_BEFORE_1.0.0> sudo apt-mark hold concert

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list concert sudo dnf downgrade concert-<VERSION_BEFORE_1.0.0> sudo dnf versionlock add concert

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-6730?

concert: upgrade to newer than 3.0.0. Exact commands for each OS are on this page.

Is CVE-2026-6730 being exploited?

CVE-2026-6730 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-6730 affect?

CVE-2026-6730 affects concert. Severity is 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 could overflow the buffer and execute arbitrary code on the system.

How urgent is CVE-2026-6730?

Priority 45/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-6928 CRITICAL 9.8 UPGRADE IBM Concert 1.0.0 through 3.0.0 references or accesses memory after it has been freed
CVE-2026-6935 HIGH 7.8 UPGRADE IBM Concert 1.0.0 through 3.0.0 invokes operating system commands without fully qualifying executable paths or
CVE-2026-6544 MEDIUM 6.2 UPGRADE IBM Concert 1.0.0 through 3.0.0 allows recursive copying of directories without proper controls which can lead
CVE-2026-6925 MEDIUM 5.3 UPGRADE IBM Concert 1.0.0 through 3.0.0 could allow a remote attacker to traverse directories on the system
CVE-2026-6794 HIGH 7.8 UPGRADE IBM Concert 1.0.0 through 3.0.0 has a double free vulnerability that exists due to incorrect memory management

References

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