CVE-2025-27571Network attack vector

Archived-channel metadata disclosure via omitted permission check

Published Apr 16, 2025 · Updated Apr 16, 2025

Incorrect authorization in affected Mattermost releases allows remote authenticated users to read metadata from archived channels. The SessionHasPermissionToChannel and SessionHasPermissionToChannels paths omitted the ExperimentalViewArchivedChannels check before granting access to archived channel objects. Mattermost 9.11.0 through 9.11.9, 10.4.0 through 10.4.3, and 10.5.0 through 10.5.1 are affected when a valid account exists and the setting is false; no content modification is reported.

CVSS severity4.3
Medium
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect authorization in affected Mattermost releases allows remote authenticated users to read metadata from archived channels. The SessionHasPermissionToChannel and SessionHasPermissionToChannels paths omitted the ExperimentalViewArchivedChannels check before granting access to archived channel objects. Mattermost 9.11.0 through 9.11.9, 10.4.0 through 10.4.3, and 10.5.0 through 10.5.1 are affected when a valid account exists and the setting is false; no content modification is reported.

The record

CVE
CVE-2025-27571
Published
Apr 16, 2025
Updated
Apr 16, 2025
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-863, T1213
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 16, 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=10.4.0 <=10.4.3
  2. Affected versionversion=10.5.0 <=10.5.1
  3. Affected versionversion=9.11.0 <=9.11.9

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=10.4.0 <=10.4.3; version=10.5.0 <=10.5.1; version=9.11.0 <=9.11.9

Published CVSS scores

4.3Mattermost, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/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.

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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-863Incorrect Authorization
T1213Data from Information Repositories

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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