CVE-2026-21388

mediumpriority · track · 26EPSS 0.003 · 24 %ileDEEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.31% (24th) EPSS

CVSS 6.5 · medium

Is it mine?

5 products

Check your exposure

Who says so?

5 sources

cnnvd · enisa_euvd · osv · cert_bund

EPSS · scored 2026-10-27

Mattermost Plugins versions <=2.3.1 fail to limit the request body size on the {{/lifecycle}} webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00610

cvss

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

6.5

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 3.7–6.5

v3.16.5mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:Hprimary · NVD / NIST USexploitability 2.8 · impact 3.6

v3.13.7lowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · ENISA EU

v3.13.7lowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · responsibledisclosure@mattermost.comexploitability 2.2 · impact 1.4

v3.13.7lowCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Lsecondary · OSV

v3.16mediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/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-770USCWE-770US

affected products (5)

Products and version ranges known to be affected.

Mattermost Mattermost MS Teams plugin <2.3.2.0all versionscert_bundDE
Mattermost Mattermost≤ MS Teams plugin <2.3.2.0cert_bundDE
Mattermost Mattermost≤ 0 ≤2.3.1enisa_euvdEU
mattermost mattermost server≤ 2.3.1nvdUScpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Go github.com/mattermost/mattermost-plugin-msteams< 1.15.1-0.20260213190728-6fe4d295592eosvUSpkg:golang/github.com/mattermost/mattermost-plugin-msteams

advisories (3)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2026-0692Mattermost MS Teams plugin: Mehrere Schwachstellen ermöglichen Denial of ServiceDeutsch2026-03-10csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen im Mattermost MS Teams plugin ausnutzen, um einen Denial of Service Angriff durchzuführen.
GHSA-x274-8qfc-hrgfMattermost MS Teams plugin doesn't limit the request body size on the /lifecycle webhook endpoint 2026-04-09ghsa · osvUS
Mattermost Plugins versions <=2.3.1 fail to limit the request body size on the {{/lifecycle}} webhook endpoint which allows an authenticated attacker to cause memory exhaustion and denial of service via sending an oversized JSON payload. Mattermost Advisory ID: MMSA-2026-00610.
GO-2026-5734Mattermost MS Teams plugin doesn't limit the request body size on the /lifecycle webhook endpoint in github.com/mattermost/mattermost-plugin-msteams2026-06-25vendor · osvUS
Mattermost MS Teams plugin doesn't limit the request body size on the /lifecycle webhook endpoint in github.com/mattermost/mattermost-plugin-msteams

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 2026-04-09modified 2026-06-17

references (3)

External citations — patches, advisories, analysis.

scry

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