CVE-2026-9820Network attack vector

Private-team access via exposed invite identifiers

Published Jul 13, 2026 · Updated Jul 13, 2026

Authorization bypass in Mattermost 10.11.0 through 10.11.19 and 11.7.0 through 11.7.2 allows remote authenticated users to obtain private-team links. The schemes teams endpoint returns unsanitized team objects containing invite identifiers to User Managers instead of removing that restricted field. The User Manager role is required; a disclosed link lets its holder join the private team or share entry with another account.

CVSS severity3.8
Low
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authorization bypass in Mattermost 10.11.0 through 10.11.19 and 11.7.0 through 11.7.2 allows remote authenticated users to obtain private-team links. The schemes teams endpoint returns unsanitized team objects containing invite identifiers to User Managers instead of removing that restricted field. The User Manager role is required; a disclosed link lets its holder join the private team or share entry with another account.

The record

CVE
CVE-2026-9820
Published
Jul 13, 2026
Updated
Jul 13, 2026
Vendor
Mattermost
Product
Mattermost
Classifications
CWE-862
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 13, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 13, 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 <=10.11.19
  2. Affected versionversion=11.7.0 <=11.7.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · Mattermostversion=10.11.0 <=10.11.19; version=11.7.0 <=11.7.2

Published CVSS scores

3.8Mattermost, Inc.CVSS:3.1/AV:N/AC:L/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.

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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-862Missing Authorization

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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