Mattermost up to 11.7.x Websocket Connection session expiration

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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4.2$0-$5k5.76-

Summaryinfo

A vulnerability classified as problematic was found in Mattermost up to 10.11.17/11.5.5/11.6.2/11.7.0/11.7.x. This vulnerability affects unknown code of the component Websocket Connection Handler. Executing a manipulation can lead to session expiration. The identification of this vulnerability is CVE-2026-9162. The attack may be launched remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability has been found in Mattermost up to 10.11.17/11.5.5/11.6.2/11.7.0/11.7.x and classified as problematic. This vulnerability affects an unknown function of the component Websocket Connection Handler. The manipulation with an unknown input leads to a session expiration vulnerability. The CWE definition for the vulnerability is CWE-613. According to WASC, "Insufficient Session Expiration is when a web site permits an attacker to reuse old session credentials or session IDs for authorization." As an impact it is known to affect confidentiality. CVE summarizes:

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 invalidate cached authentication state for active WebSocket connections during global session revocation, which allows a user with an existing WebSocket connection to remain authenticated and continue receiving real-time events until the cached session expires or the client reconnects.. Mattermost Advisory ID: MMSA-2026-00664

The weakness was shared by winfunc. The advisory is available at mattermost.com. This vulnerability was named CVE-2026-9162 since 05/21/2026. The exploitation appears to be easy. The attack can be initiated remotely. The technical details are unknown and an exploit is not available.

Upgrading to version 10.11.18, 11.5.6, 11.6.3, 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: 4.3
VulDB Meta Temp Score: 4.2

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 4.3
CNA Vector (Mattermost): 🔒

CVSSv2info

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

Exploitinginfo

Class: Session expiration
CWE: CWE-613
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

05/21/2026 CVE reserved
06/22/2026 +32 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: winfunc
Status: Confirmed

CVE: CVE-2026-9162 (🔒)
GCVE (CVE): GCVE-0-2026-9162
GCVE (VulDB): GCVE-100-372694

Entryinfo

Created: 06/22/2026 17:29
Changes: 06/22/2026 17:29 (64)
Complete: 🔍
Cache ID: 216::103

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