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Medium 4.3Published May 18, 2026

CVE-2026-6342Mattermost Plugins versions <=11.5 11.1.5 10.13.11 11.3.4.0 fail to appropriately check for valid namespaces which allows plugin users to create subscriptions to groups that were not whitelisted via…

Updated under an hour ago ()

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It affects mattermost_server. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Mattermost Plugins versions <=11.5 11.1.5 10.13.11 11.3.4.0 fail to appropriately check for valid namespaces which allows plugin users to create subscriptions to groups that were not whitelisted via creating groups that share the same prefix as a whitelisted group. Mattermost Advisory ID: MMSA-2026-00601

CVSS
4.3 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Weakness (CWE)
CWE-863
Known exploited
Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days)
Not loaded for this CVE
Assigned by
Not given
NVD analysis
Analyzed
Record last updated
Oct 14, 2026
First seen by InfoSec Signals
Oct 9, 2026

Affected products

Affected products
mattermost mattermost_server
mattermost:mattermost_server
from 10.13.0 through 10.13.11; from 11.1.0 through 11.1.5; from 11.3.0 through 11.3.4
NVD

References

  • vendor-advisory

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.

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