Mattermost up to 11.7.x missing authentication

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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5.9$0-$5k2.57-

Summaryinfo

A vulnerability identified as critical has been detected in Mattermost up to 10.11.17/11.5.5/11.6.2/11.7.0/11.7.x. This impacts an unknown function. The manipulation leads to missing authentication. This vulnerability is traded as CVE-2026-6673. It is possible to initiate the attack remotely. There is no exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Mattermost up to 10.11.17/11.5.5/11.6.2/11.7.0/11.7.x. It has been rated as critical. This issue affects some unknown functionality. 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, integrity, and availability. The summary by CVE is:

Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to authenticate Atlassian Connect installed callbacks, allowing a remote unauthenticated attacker to inject a rogue sharedSecret and disrupt the Jira integration via POST to /ac/installed during the pending-install window.. Mattermost Advisory ID: MMSA-2026-00654

The weakness was shared by insomnia1102. The advisory is shared at mattermost.com. The identification of this vulnerability is CVE-2026-6673 since 04/20/2026. The exploitation is known to be difficult. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Neither technical details nor an exploit are publicly available.

Upgrading to version 10.11.18, 11.5.6, 11.6.3, 11.7.1 or 11.8.0 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.0
VulDB Meta Temp Score: 5.9

VulDB Base Score: 5.6
VulDB Temp Score: 5.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 6.4
CNA Vector (Mattermost): 🔒

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
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
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 10.11.18/11.5.6/11.6.3/11.7.1/11.8.0

Timelineinfo

04/20/2026 CVE reserved
06/22/2026 +63 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: insomnia1102
Status: Confirmed

CVE: CVE-2026-6673 (🔒)
GCVE (CVE): GCVE-0-2026-6673
GCVE (VulDB): GCVE-100-372689

Entryinfo

Created: 06/22/2026 17:27
Changes: 06/22/2026 17:27 (64)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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