CVE-2026-3524Network attack vector

Authenticated data theft and deletion via missing return

Published Apr 6, 2026 · Updated Apr 6, 2026

Missing authorization in Mattermost Plugin Legal Hold 1.1.4 and earlier allows remote authenticated users to alter or obtain legal hold data. ServeHTTP writes a failed permission response but does not return, so the same crafted API request continues into handlers that access, create, download, or delete protected hold data. Any authenticated account can reach the plugin route; consequences include disclosure, unauthorized hold creation, and permanent deletion of preserved data.

CVSS severity8.8
High
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing authorization in Mattermost Plugin Legal Hold 1.1.4 and earlier allows remote authenticated users to alter or obtain legal hold data. ServeHTTP writes a failed permission response but does not return, so the same crafted API request continues into handlers that access, create, download, or delete protected hold data. Any authenticated account can reach the plugin route; consequences include disclosure, unauthorized hold creation, and permanent deletion of preserved data.

The record

CVE
CVE-2026-3524
Published
Apr 6, 2026
Updated
Apr 6, 2026
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-862, T1213.005, T1565.001
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 6, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 6, 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?

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

  1. Affected versionversion=0 <=1.1.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=0 <=1.1.4

Published CVSS scores

8.8Mattermost, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-862Missing Authorization
T1213.005Data from Information Repositories: Messaging Applications
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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