CVE-2026-6046

EUVD-2026-36502
Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 fail to validate that a username returned during bot registration belongs to a bot account, which allows an unprivileged attacker to intercept private messages sent by plugins via direct message channels by pre-registering a user account with a predictable plugin bot username.. Mattermost Advisory ID: MMSA-2026-00649
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
MattermostCNA
5.3 MEDIUM
NETWORK
HIGH
LOW
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
Base Score
CVSS 3.x
EPSS Score
Percentile: Unknown
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
mattermostmattermost
11.6.0 ≤
𝑥
≤ 11.6.1
CNA
mattermostmattermost
11.5.0 ≤
𝑥
≤ 11.5.4
CNA
mattermostmattermost
10.11.0 ≤
𝑥
≤ 10.11.15
CNA
mattermostmattermost
10.11.0 ≤
𝑥
≤ 10.11.16
CNA