CVE-2025-6465Network attack vector

Thumbnail overwrite via unsanitized streaming filename

Published Aug 21, 2025 · Updated Aug 21, 2025

Path traversal in Mattermost allows remote authenticated users to overwrite file attachment thumbnails through file-streaming APIs. The file-streaming APIs resolve thumbnail destination paths from uploaded filenames without neutralizing traversal segments. The attacker must hold file-upload permission; exploitation changes an existing thumbnail and has no reported confidentiality or availability impact.

CVSS severity4.3
Medium
EPSS probability0.77%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in Mattermost allows remote authenticated users to overwrite file attachment thumbnails through file-streaming APIs. The file-streaming APIs resolve thumbnail destination paths from uploaded filenames without neutralizing traversal segments. The attacker must hold file-upload permission; exploitation changes an existing thumbnail and has no reported confidentiality or availability impact.

The record

CVE
CVE-2025-6465
Published
Aug 21, 2025
Updated
Aug 21, 2025
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-22, CAPEC-126, T1565.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 21, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 21, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.10.0
  2. Affected versionversion=10.5.0 <=10.5.8
  3. Affected versionversion=10.8.0 <=10.8.3
  4. Affected versionversion=10.9.0 <=10.9.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=10.10.0; version=10.5.0 <=10.5.8; version=10.8.0 <=10.8.3; version=10.9.0 <=10.9.3

Published CVSS scores

4.3MattermostCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CAPEC-126Path Traversal
T1565.001Stored Data Manipulation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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