How severe is CVE-2024-39274?

CVE-2024-39274 has a CVSS 3.x base score of 8.7, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.

Is CVE-2024-39274 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (26th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2024-39274?

CVE-2024-39274 primarily affects Mattermost. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2024-39274?

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

Does CVE-2024-39274 have an EU (EUVD) identifier?

Yes. CVE-2024-39274 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-2562.

When was CVE-2024-39274 published?

CVE-2024-39274 was published on 2024-08-01 and last updated on 2026-06-17.

CVE-2024-39274

CVE-2024-39274 is a high-severity vulnerability in Mattermost with a CVSS 3.x base score of 8.7. 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-284.

Key facts

Severity: High (CVSS 3.x base score 8.7)
EPSS exploit prediction: 0% (26th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2024-2562
Weakness: CWE-284
Affected product: Mattermost
Published: 2024-08-01
Last modified: 2026-06-17

Description

Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6, 9.7.x <= 9.7.5 and 9.8.x <= 9.8.1 fail to properly validate that the channel that comes from the sync message is a shared channel, when shared channels are enabled, which allows a malicious remote to add users to arbitrary teams and channels

Frequently asked questions

What is CVE-2024-39274?: Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6, 9.7.x <= 9.7.5 and 9.8.x <= 9.8.1 fail to properly validate that the channel that comes from the sync message is a shared channel, when shared channels are enabled, which allows a malicious remote to add users to arbitrary teams and channels
How severe is CVE-2024-39274?: CVE-2024-39274 has a CVSS 3.x base score of 8.7, rated high severity. It is exploitable over network with low attack complexity, requires high privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability none.
Is CVE-2024-39274 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (26th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2024-39274?: CVE-2024-39274 primarily affects Mattermost. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2024-39274?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2024-39274 have an EU (EUVD) identifier?: Yes. CVE-2024-39274 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2024-2562.
When was CVE-2024-39274 published?: CVE-2024-39274 was published on 2024-08-01 and last updated on 2026-06-17.

References

https://mattermost.com/security-updates

Affected products (2)

cpe:2.3:a:mattermost:mattermost:*:*:*:*:*:*:*:*
cpe:2.3:a:mattermost:mattermost:9.9.0:*:*:*:*:*:*:*

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