Mattermost up to 10.10.1 Channel Membership authorization

CVSS Meta Temp Score
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CTI Interest Score
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5.5$0-$5k0.00

Summaryinfo

A vulnerability was found in Mattermost up to 10.10.1. It has been declared as problematic. Affected by this issue is some unknown functionality of the component Channel Membership Handler. Executing a manipulation can lead to authorization. This vulnerability is handled as CVE-2025-9076. The attack can be executed remotely. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Mattermost up to 10.10.1 and classified as problematic. This vulnerability affects some unknown processing of the component Channel Membership Handler. The manipulation with an unknown input leads to a authorization vulnerability. The CWE definition for the vulnerability is CWE-862. The product does not perform an authorization check when an actor attempts to access a resource or perform an action. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

Mattermost versions 10.10.x <= 10.10.1 fail to properly sanitize user data during shared channel membership synchronization, which allows malicious or compromised remote clusters to access sensitive user information via unsanitized user objects. This vulnerability affects Mattermost Server instances with shared channels enabled.

The weakness was released by daw10. The advisory is shared for download at mattermost.com. This vulnerability was named CVE-2025-9076 since 08/15/2025. The exploitation appears to be easy. The attack can be initiated remotely. The exploitation needs additional levels of successful authentication. There are neither technical details nor an exploit publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 266219 (Mattermost Server 10.10.x < 10.10.2 / 10.11.0 Missing Authorization (MMSA-2025-00513)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 10.10.2 or 10.11.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (266219). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.6
VulDB Meta Temp Score: 5.5

VulDB Base Score: 4.7
VulDB Temp Score: 4.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 6.5
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-862 / CWE-863 / CWE-285
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 266219
Nessus Name: Mattermost Server 10.10.x < 10.10.2 / 10.11.0 Missing Authorization (MMSA-2025-00513)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Mattermost 10.10.2/10.11.0

Timelineinfo

08/15/2025 CVE reserved
09/15/2025 +31 days Advisory disclosed
09/15/2025 +0 days VulDB entry created
10/02/2025 +17 days VulDB entry last update

Sourcesinfo

Advisory: mattermost.com
Researcher: daw10
Status: Confirmed

CVE: CVE-2025-9076 (🔒)
GCVE (CVE): GCVE-0-2025-9076
GCVE (VulDB): GCVE-100-323896

Entryinfo

Created: 09/15/2025 14:48
Updated: 10/02/2025 19:34
Changes: 09/15/2025 14:48 (64), 10/02/2025 19:34 (2)
Complete: 🔍
Cache ID: 216::103

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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