Prevent password disclosure and force reset during Slack import

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Summary

CVECVE-2026-6345
StatePUBLISHED
AssignerMattermost
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-18 09:16:23 UTC
Updated2026-05-18 19:05:22 UTC
DescriptionMattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 fail prevent disclosure of created user password which allows a malicious attacker to impersonate a user via the use of some of those passwords.. Mattermost Advisory ID: MMSA-2026-00614

Risk And Classification

Primary CVSS: v3.1 6.5 MEDIUM from [email protected]

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

EPSS: 0.000360000 probability, percentile 0.108920000 (date 2026-05-26)

Problem Types: CWE-522 | CWE-522 CWE-522: Insufficiently Protected Credentials

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N
3.1CNACVSS6.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:N

CVSS v3.1 Breakdown

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

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

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: eeshan (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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