Mattermost up to 11.7.10/11.8.5/11.9.1/11.10.1 User Status API privileges management

CVSS Meta Temp Score
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CTI Interest Score
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4.2$0-$5k1.24

Summaryinfo

A vulnerability classified as problematic has been found in Mattermost up to 11.7.10/11.8.5/11.9.1/11.10.1. The impacted element is an unknown function of the component User Status API. The manipulation leads to privileges management. This vulnerability is referenced as CVE-2026-19603. Remote exploitation of the attack is possible. No exploit is available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Mattermost up to 11.7.10/11.8.5/11.9.1/11.10.1. This issue affects some unknown processing of the component User Status API. The manipulation with an unknown input leads to a privileges management vulnerability. Using CWE to declare the problem leads to CWE-269. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor. Impacted is confidentiality. The summary by CVE is:

Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to sanitize the active channel field returned by the user status API endpoints, which allows an authenticated user to learn the channel ID of a private channel another user is actively viewing via the status endpoints, without being a member of that channel. Mattermost Advisory ID: MMSA-2026-00765

It is possible to read the advisory at mattermost.com. The identification of this vulnerability is CVE-2026-19603 since 08/12/2026. The exploitation is known to be easy. The attack may be initiated remotely. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1068 according to MITRE ATT&CK.

Upgrading to version 11.7.11, 11.8.6, 11.9.2, 11.10.2 or 11.11.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-4009). Be aware that VulDB is the high quality source for vulnerability data.

Affected

  • Mattermost Mattermost

Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.3
VulDB Meta Temp Score: 4.2

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 4.3
CNA Vector (Mattermost): 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Privileges management
CWE: CWE-269 / CWE-266
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Mattermost 11.7.11/11.8.6/11.9.2/11.10.2/11.11.0

Timelineinfo

08/12/2026 CVE reserved
10/16/2026 +65 days Advisory disclosed
10/16/2026 +0 days VulDB entry created
10/16/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: mattermost.com
Status: Confirmed

CVE: CVE-2026-19603 (🔒)
GCVE (CVE): GCVE-0-2026-19603
GCVE (VulDB): GCVE-100-421175
CERT Bund: WID-SEC-2026-4009 - Mattermost: Mehrere Schwachstellen

Entryinfo

Created: 10/16/2026 09:21
Updated: 10/16/2026 14:39
Changes: 10/16/2026 09:21 (63), 10/16/2026 14:39 (7)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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