CVE-2026-16044Network attack vector

Board Admin escalation via unvalidated archive roles

Published Aug 17, 2026 · Updated Aug 17, 2026

Incorrect authorization in Mattermost 10.11.0 through 10.11.21 and 11.7.0 through 11.7.6 allows attackers to grant guests Board Admin. The board archive importer accepts role data from a crafted .boardarchive file without rejecting a guest assignment to the Board Admin role. Remote authenticated users must already be board members and can elevate a guest's board-scoped permissions, enabling unauthorized board operations.

CVSS severity5.4
Medium
EPSS probability0.17%
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 10.11.0 through 10.11.21 and 11.7.0 through 11.7.6 allows attackers to grant guests Board Admin. The board archive importer accepts role data from a crafted .boardarchive file without rejecting a guest assignment to the Board Admin role. Remote authenticated users must already be board members and can elevate a guest's board-scoped permissions, enabling unauthorized board operations.

The record

CVE
CVE-2026-16044
Published
Aug 17, 2026
Updated
Aug 17, 2026
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-863, T1068
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 17, 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=10.11.0 <=10.11.21
  2. Affected versionversion=11.7.0 <=11.7.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=10.11.0 <=10.11.21; version=11.7.0 <=11.7.6

Published CVSS scores

5.4Mattermost, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L

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-863Incorrect Authorization
T1068Exploitation for Privilege Escalation

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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