CVE-2026-6046

mediumpriority · track · 0EPSS 0.003 · 22 %ileDEEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.30% (22nd) EPSS

CVSS 5.3 · medium

Is it mine?

24 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · osv · cert_bund

EPSS · scored 2026-10-22

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

cvss

Technical severity, 0–10. One row per scoring source.

5.3

010

base score 0–10 · higher = more severe · hover a vector to decode

v3.15.3mediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:Nsecondary · ENISA EU

v3.15.3mediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:Nsecondary · responsibledisclosure@mattermost.comexploitability 1.6 · impact 3.6

v3.15.3mediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:Nsecondary · OSV

v3.14.9mediumCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-200USCWE-200US

affected products (24)

Products and version ranges known to be affected.

Mattermost Mattermost Server <10.11.17all versionscert_bundDE
Mattermost Mattermost Server <11.5.5all versionscert_bundDE
Mattermost Mattermost Server <11.6.2all versionscert_bundDE
Mattermost Mattermost Server <11.7.0all versionscert_bundDE
Mattermost Mattermost≤ Server <10.11.17cert_bundDE
Mattermost Mattermost≤ Server <11.5.5cert_bundDE
Mattermost Mattermost≤ Server <11.6.2cert_bundDE
Mattermost Mattermost≤ Server <11.7.0cert_bundDE
Mattermost Mattermost≤ 11.6.0 ≤11.6.1enisa_euvdEU
Mattermost Mattermost≤ 11.5.0 ≤11.5.4enisa_euvdEU
Mattermost Mattermost≤ 10.11.0 ≤10.11.15enisa_euvdEU
Mattermost Mattermost≤ 10.11.0 ≤10.11.16enisa_euvdEU
mattermost mattermost server10.11.0 → 10.11.17nvdUScpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
mattermost mattermost server11.5.0 → 11.5.5nvdUScpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
mattermost mattermost server11.6.0 → 11.6.2nvdUScpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Go github.com/mattermost/mattermost-server10.11.0 → 10.11.17osvUSpkg:golang/github.com/mattermost/mattermost-server
Go github.com/mattermost/mattermost-server10.11.0+incompatible → 10.11.17+incompatibleosvUSpkg:golang/github.com/mattermost/mattermost-server
Go github.com/mattermost/mattermost-server11.5.0 → 11.5.5osvUSpkg:golang/github.com/mattermost/mattermost-server
Go github.com/mattermost/mattermost-server11.5.0+incompatible → 11.5.5+incompatibleosvUSpkg:golang/github.com/mattermost/mattermost-server
Go github.com/mattermost/mattermost-server11.6.0 → 11.6.1osvUSpkg:golang/github.com/mattermost/mattermost-server

showing 20 of 24

advisories (3)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2026-1529Mattermost Server: Mehrere Schwachstellen ermöglichen nicht spezifizierten AngriffDeutsch2026-05-14csaf · cert_bundDE
Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Mattermost Server ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen.
GHSA-3vmp-whvv-5v9vMattermost doesn't validate that a username returned during bot registration belongs to a bot account2026-06-12ghsa · osvUS
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
GO-2026-6279Mattermost doesn't validate that a username returned during bot registration belongs to a bot account in github.com/mattermost/mattermost-server2026-08-25vendor · osvUS
Mattermost doesn't validate that a username returned during bot registration belongs to a bot account in github.com/mattermost/mattermost-server

also known as (5)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd osv cert_bund nvd NVD CVE.org MITRE

published 2026-06-12modified 2026-06-18

references (3)

External citations — patches, advisories, analysis.

scry

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