Mattermost up to 10.11.19/11.6.4/11.7.2 Incoming Webhook permission

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
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CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.0$0-$5k0.52+

Summaryinfo

A vulnerability has been found in Mattermost up to 10.11.19/11.6.4/11.7.2 and classified as critical. The affected element is an unknown function of the component Incoming Webhook Handler. The manipulation leads to permission. This vulnerability is listed as CVE-2026-9708. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in Mattermost up to 10.11.19/11.6.4/11.7.2 and classified as critical. This issue affects an unknown part of the component Incoming Webhook Handler. The manipulation with an unknown input leads to a permission vulnerability. Using CWE to declare the problem leads to CWE-275. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to validate that an assigned incoming webhook user has access to the target team or channel, which allows a requester with webhook management permissions to create posts or direct messages attributed to another user via crafted incoming webhook configuration and payloads.. Mattermost Advisory ID: MMSA-2026-00683

The advisory is shared at mattermost.com. The identification of this vulnerability is CVE-2026-9708 since 05/27/2026. The exploitation is known to be easy. The attack may be initiated remotely. Neither technical details nor an exploit are publicly available. MITRE ATT&CK project uses the attack technique T1222 for this issue.

Upgrading to version 10.11.20, 11.6.5, 11.7.3 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: 6.3
VulDB Meta Temp Score: 6.0

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Exploitinginfo

Class: Permission
CWE: CWE-275 / 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: no mitigation known
Status: 🔍

0-Day Time: 🔒

Upgrade: Mattermost 10.11.20/11.6.5/11.7.3/11.8.0

Timelineinfo

05/27/2026 CVE reserved
07/13/2026 +47 days Advisory disclosed
07/13/2026 +0 days VulDB entry created
07/13/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: mattermost.com
Status: Confirmed

CVE: CVE-2026-9708 (🔒)
GCVE (CVE): GCVE-0-2026-9708
GCVE (VulDB): GCVE-100-377933

Entryinfo

Created: 07/13/2026 11:16
Changes: 07/13/2026 11:16 (53)
Complete: 🔍
Cache ID: 216::103

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