CVE-2026-10080Network attack vector

Authenticated DoS via unchecked WebSocket teamId type

Published Aug 17, 2026 · Updated Aug 18, 2026

Denial of service in Mattermost before 10.11.22, 11.7.7, and 11.8.4 allows remote authenticated users to crash Boards via a crafted WebSocket message. The Boards WebSocket handler for custom_focalboard_SUBSCRIBE_TEAM does not verify that teamId is a string before using it as one, so a malformed command panics the plugin process. Any authenticated account that can send the message can interrupt Boards for all users on that server, with no evidence of data exposure or code execution.

CVSS severity6.5
Medium
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Mattermost before 10.11.22, 11.7.7, and 11.8.4 allows remote authenticated users to crash Boards via a crafted WebSocket message. The Boards WebSocket handler for custom_focalboard_SUBSCRIBE_TEAM does not verify that teamId is a string before using it as one, so a malformed command panics the plugin process. Any authenticated account that can send the message can interrupt Boards for all users on that server, with no evidence of data exposure or code execution.

The record

CVE
CVE-2026-10080
Published
Aug 17, 2026
Updated
Aug 18, 2026
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-704, T1499
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 18, 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
  3. Affected versionversion=11.8.0 <=11.8.3

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; version=11.8.0 <=11.8.3

Published CVSS scores

6.5MattermostCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/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 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-704Incorrect Type Conversion or Cast
T1499Endpoint Denial of Service

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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