Mattermost Calls plugin exposes TURN server credentials in plaintext in support packets

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Summary

CVECVE-2026-6347
StatePUBLISHED
AssignerMattermost
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-18 09:16:24 UTC
Updated2026-05-18 18:39:43 UTC
DescriptionMattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail to sanitize sensitive configuration fields in the Mattermost Calls plugin which allows an attacker with access to a support packet to obtain TURN server credentials via the plaintext values present in the exported plugin configuration.. Mattermost Advisory ID: MMSA-2026-00605

Risk And Classification

Primary CVSS: v3.1 7.6 HIGH from [email protected]

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

EPSS: 0.000530000 probability, percentile 0.165620000 (date 2026-05-26)

Problem Types: CWE-200 | CWE-200 CWE-200 Exposure of Sensitive Information to an Unauthorized Actor

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.6HIGHCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:L
3.1CNACVSS7.6HIGHCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
None
Availability
Low

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

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Mattermost Mattermost Server All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Mattermost Mattermost affected 11.5.0 11.5.1 semver Not specified
CNA Mattermost Mattermost affected 10.11.0 10.11.13 semver Not specified
CNA Mattermost Mattermost affected 11.4.0 11.4.3 semver Not specified
CNA Mattermost Mattermost unaffected 11.6.0 Not specified
CNA Mattermost Mattermost unaffected 11.5.2 Not specified
CNA Mattermost Mattermost unaffected 10.11.14 Not specified
CNA Mattermost Mattermost unaffected 11.4.4 Not specified

References

ReferenceSourceLinkTags
mattermost.com/security-updates [email protected] mattermost.com Vendor Advisory
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Edgar Bellot Micó (en)

Additional Advisory Data

Solutions

CNA: Update Mattermost to versions 11.6.0, 11.5.2, 10.11.14, 11.4.4 or higher.

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