CVE-2026-6961: Path traversal via unsanitized FileInfo.Name in Mattermost federation sync

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Summary

CVECVE-2026-6961
StatePUBLISHED
AssignerMattermost
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-12 17:16:27 UTC
Updated2026-06-18 14:40:29 UTC
DescriptionMattermost 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 Mattermost fails to sanitize FileInfo.Name received from federated peers during shared channel file sync, which allows an attacker who controls a federated server to write files to arbitrary locations within the target server's filestore via path traversal sequences in the filename field.. Mattermost Advisory ID: MMSA-2026-00661

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:N/I:H/A:L

EPSS: 0.002940000 probability, percentile 0.208140000 (date 2026-06-22)

Problem Types: CWE-22 | CWE-22 CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

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

CVSS v3.1 Breakdown

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

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:N/I:H/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 11.6.0 11.6.1 semver Not specified
CNA Mattermost Mattermost affected 11.5.0 11.5.4 semver Not specified
CNA Mattermost Mattermost affected 10.11.0 10.11.15 semver Not specified
CNA Mattermost Mattermost affected 10.11.0 10.11.16 semver Not specified
CNA Mattermost Mattermost unaffected 11.7.0 Not specified
CNA Mattermost Mattermost unaffected 11.6.2 Not specified
CNA Mattermost Mattermost unaffected 11.5.5 Not specified
CNA Mattermost Mattermost unaffected 10.11.16 Not specified
CNA Mattermost Mattermost unaffected 10.11.17 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: Hassan Mohammed (en)

Additional Advisory Data

Solutions

CNA: Update Mattermost to versions 11.7.0, 11.6.2, 11.5.5, 10.11.16, 10.11.17 or higher.

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