GHSA-3vmp-whvv-5v9vPublished

Plugin bot username conflict allows user account to be used as bot identity in Mattermost Server

Exploitation and risk

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cve-program · CVE-2026-6046

Published

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

Source published: 12 Jun 2026 15:52:33 UTC
Source modified: 12 Jun 2026 17:18:30 UTC
Saved here: 23 Oct 2026 15:48:27 UTC
Source terms: CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

euvd · EUVD-2026-36502

Published

Additional publisher context

EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.

Original publisher date fields

datePublished: Jun 12, 2026, 3:52:33 PM

dateUpdated: Jun 12, 2026, 5:18:30 PM

1 related source bulletins · separate from aliases

WID-SEC-W-2026-1529: Mattermost Server: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff

CVE-2026-3433 · CVE-2026-6046 · CVE-2026-6689 · CVE-2026-6739 · CVE-2026-6961 · CVE-2026-7387

Source published: Jun 12, 2026, 3:52:33 PM (timezone not stated)
Source modified: Jun 12, 2026, 5:18:30 PM (timezone not stated)
Saved here: 15 Nov 2026 17:54:03 UTC
Source terms: ENISA EUVD · source terms and attribution apply

Original source record · Cite this exact observation · Complete original publisher JSON

Source: euvd · ENISA EUVD · source terms and attribution apply. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

EUVD CVSS 3.1 · 5.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

nvd · CVE-2026-6046

Published

Additional publisher context

NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.

Source analysis status: Analyzed

Weakness classifications: CWE-200

Original publisher date fields

published: 2026-06-12T17:16:26.957

lastModified: 2026-06-18T14:33:35.203

1 source CPE criteria · context only

cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*

The original JSON retains the logical configuration operators, exclusions and version bounds.

Source published: 12 Jun 2026 17:16:26 UTC
Source modified: 18 Jun 2026 14:33:35 UTC
Saved here: 25 Oct 2026 14:19:22 UTC
Source terms: NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

Source: nvd · NIST NVD usage terms; underlying source attribution retained. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS 3.1 · [email protected] · Secondary · 5.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

osv · GHSA-3vmp-whvv-5v9v

Published

Source published: 12 Jun 2026 18:31:59 UTC
Source modified: 10 Sep 2026 03:50:55 UTC
Saved here: 24 Oct 2026 13:19:41 UTC
Source terms: GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

Source: osv · GitHub Advisory Database · CC-BY-4.0. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.

CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

Publisher rating · MODERATE

osv · GO-2026-6279

Published

Mattermost doesn't validate that a username returned during bot registration belongs to a bot account in github.com/mattermost/mattermost-server

Source published: 25 Aug 2026 19:43:10 UTC
Source modified: 26 Aug 2026 01:13:10 UTC
Saved here: 24 Oct 2026 13:19:41 UTC
Source terms: OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

Source: osv · OSV · upstream source license applies. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.