CVE-2025-27715Network attack vector

Private-channel access via unconfirmed permalink enrollment

Published Mar 21, 2025 · Updated Mar 21, 2025

Incorrect authorization in Mattermost 9.11.0 through 9.11.8 allows remote authenticated users to join private channels via crafted permalinks. The permalink channel-resolution flow treats team-admin status as sufficient authorization and adds the account to the referenced private channel without an explicit approval prompt. A team-admin account and a valid private-channel permalink are required; successful exploitation grants unintended membership and access to channel content.

CVSS severity3.3
Low
EPSS probability0.21%
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 Mattermost 9.11.0 through 9.11.8 allows remote authenticated users to join private channels via crafted permalinks. The permalink channel-resolution flow treats team-admin status as sufficient authorization and adds the account to the referenced private channel without an explicit approval prompt. A team-admin account and a valid private-channel permalink are required; successful exploitation grants unintended membership and access to channel content.

The record

CVE
CVE-2025-27715
Published
Mar 21, 2025
Updated
Mar 21, 2025
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-863, T1213.005
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Mar 21, 2025CVE publishedPublication date reported by the CVE source.
  2. Mar 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=9.11.0 <=9.11.8

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

Mattermost · Mattermostversion=9.11.0 <=9.11.8

Published CVSS scores

2.7NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:N
3.3MattermostCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-863Incorrect Authorization
T1213.005Data from Information Repositories: Messaging Applications

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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