Mattermost up to 9.11.16/10.5.6/10.7.3/10.8.1 Private Channel missing authentication

CVSS Meta Temp Score
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CTI Interest Score
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5.8$0-$5k0.00

Summaryinfo

A vulnerability identified as critical has been detected in Mattermost up to 9.11.16/10.5.6/10.7.3/10.8.1. Impacted is an unknown function of the component Private Channel Handler. The manipulation leads to missing authentication. This vulnerability is documented as CVE-2025-6226. The attack can be initiated remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Mattermost up to 9.11.16/10.5.6/10.7.3/10.8.1. It has been rated as critical. This issue affects some unknown functionality of the component Private Channel Handler. The manipulation with an unknown input leads to a missing authentication vulnerability. Using CWE to declare the problem leads to CWE-306. The product does not perform any authentication for functionality that requires a provable user identity or consumes a significant amount of resources. Impacted is confidentiality. The summary by CVE is:

Mattermost versions 10.5.x <= 10.5.6, 10.8.x <= 10.8.1, 10.7.x <= 10.7.3, 9.11.x <= 9.11.16 fail to verify authorization when retrieving cached posts by PendingPostID which allows an authenticated user to read posts in private channels they don't have access to via guessing the PendingPostID of recently created posts.

The weakness was released by Dawid Kulikowski. It is possible to read the advisory at mattermost.com. The identification of this vulnerability is CVE-2025-6226 since 06/18/2025. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. The technical details are unknown and an exploit is not publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 242670 (Mattermost Server 9.11.x < 9.11.17 / 10.5.x < 10.5.7 / 10.7.x < 10.7.4 / 10.8.x < 10.8.2 (MMSA-2025-00490)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 9.11.17, 10.5.7, 10.7.4, 10.8.2 or 10.9.0 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (242670) and EUVD (EUVD-2025-21867). Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.9
VulDB Meta Temp Score: 5.8

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
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: Missing authentication
CWE: CWE-306 / CWE-287
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: 242670
Nessus Name: Mattermost Server 9.11.x < 9.11.17 / 10.5.x < 10.5.7 / 10.7.x < 10.7.4 / 10.8.x < 10.8.2 (MMSA-2025-00490)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Mattermost 9.11.17/10.5.7/10.7.4/10.8.2/10.9.0

Timelineinfo

06/18/2025 🔍
07/18/2025 +30 days 🔍
07/18/2025 +0 days 🔍
07/25/2025 +6 days 🔍

Sourcesinfo

Advisory: mattermost.com
Researcher: Dawid Kulikowski
Status: Confirmed

CVE: CVE-2025-6226 (🔍)
GCVE (CVE): GCVE-0-2025-6226
GCVE (VulDB): GCVE-100-316871
EUVD: 🔍

Entryinfo

Created: 07/18/2025 11:39
Updated: 07/25/2025 00:43
Changes: 07/18/2025 11:39 (65), 07/18/2025 15:49 (1), 07/23/2025 01:48 (1), 07/25/2025 00:43 (2)
Complete: 🔍
Cache ID: 216::103

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

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