Mattermost up to 10.11.17/11.7.0/11.7.x Standard demote-user API authorization

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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3.7$0-$5k2.43-

Summaryinfo

A vulnerability was found in Mattermost up to 10.11.17/11.7.0/11.7.x. It has been declared as problematic. This issue affects some unknown processing of the component Standard demote-user API. Such manipulation leads to authorization. This vulnerability is listed as CVE-2026-8823. The attack may be performed from remote. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Mattermost up to 10.11.17/11.7.0/11.7.x. Affected by this issue is some unknown processing of the component Standard demote-user API. The manipulation with an unknown input leads to a authorization vulnerability. Using CWE to declare the problem leads to CWE-863. The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions. Impacted is integrity, and availability. CVE summarizes:

Mattermost versions 11.7.x <= 11.7.0, 10.11.x <= 10.11.17 fail to validate bot targets when demoting users to guests which allows a lower-privileged administrator to degrade arbitrary bot accounts via the standard demote-user API.. Mattermost Advisory ID: MMSA-2026-00669

The weakness was presented by Edgar Bellot Micó. The advisory is shared for download at mattermost.com. This vulnerability is handled as CVE-2026-8823 since 05/18/2026. The exploitation is known to be easy. The attack may be launched remotely. Additional levels of successful authentication are necessary for exploitation. There are neither technical details nor an exploit publicly available.

Upgrading to version 10.11.18, 11.7.1 or 11.8.0 eliminates this vulnerability.

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Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 3.8
VulDB Meta Temp Score: 3.7

VulDB Base Score: 3.8
VulDB Temp Score: 3.7
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 3.8
CNA Vector (Mattermost): 🔒

CVSSv2info

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

Exploitinginfo

Class: Authorization
CWE: CWE-863 / CWE-285 / 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 10.11.18/11.7.1/11.8.0

Timelineinfo

05/18/2026 CVE reserved
06/22/2026 +35 days Advisory disclosed
06/22/2026 +0 days VulDB entry created
06/22/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: mattermost.com
Researcher: Edgar Bellot Micó
Status: Confirmed

CVE: CVE-2026-8823 (🔒)
GCVE (CVE): GCVE-0-2026-8823
GCVE (VulDB): GCVE-100-372728

Entryinfo

Created: 06/22/2026 18:09
Changes: 06/22/2026 18:09 (64)
Complete: 🔍
Cache ID: 216::103

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