Arbitrary file write via federated filename traversal
Published May 27, 2026 · Updated May 27, 2026
Path traversal in Mattermost Legal Hold plugin 1.1.5 and earlier allows remote authenticated users to write files outside the export path. Attachment sync processing accepts a federated peer's filename without sanitizing traversal components and uses it to construct the export destination path. Exploitation requires administrative control of a federated Mattermost peer; the resulting write can target arbitrary locations within the target server's filestore.
Summary
What happened
Path traversal in Mattermost Legal Hold plugin 1.1.5 and earlier allows remote authenticated users to write files outside the export path. Attachment sync processing accepts a federated peer's filename without sanitizing traversal components and uses it to construct the export destination path. Exploitation requires administrative control of a federated Mattermost peer; the resulting write can target arbitrary locations within the target server's filestore.
The record
- CVE
- CVE-2026-6957
- Published
- May 27, 2026
- Updated
- May 27, 2026
- Vendor
- Mattermost
- Product
- Mattermost
- Classifications
- CWE-22, T1105
- Attack vector
- network
- Privileges
- admin
Timeline
How it unfolded
- May 27, 2026CVE publishedPublication date reported by the CVE source.
- May 27, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=0 <=1.1.5
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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