Mattermost up to 11.7.10/11.8.5/11.9.1/11.10.1 Internal-connection filter server-side request forgery

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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4.0$0-$5k0.37+

Summaryinfo

A vulnerability has been found in Mattermost up to 11.7.10/11.8.5/11.9.1/11.10.1 and classified as problematic. The affected element is an unknown function of the component Internal-connection filter. This manipulation causes server-side request forgery. This vulnerability appears as CVE-2026-96259. The attack may be initiated remotely. There is no available exploit. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Mattermost up to 11.7.10/11.8.5/11.9.1/11.10.1. It has been declared as problematic. Affected by this vulnerability is an unknown part of the component Internal-connection filter. The manipulation with an unknown input leads to a server-side request forgery vulnerability. The CWE definition for the vulnerability is CWE-918. The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. As an impact it is known to affect confidentiality. The summary by CVE is:

Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to apply the internal-connection filter to OAuth endpoint requests, which allows a System Administrator to make the server issue requests to internal network addresses and read the responses via the configured OAuth token and userinfo endpoints.. Mattermost Advisory ID: MMSA-2026-00776

The advisory is shared at mattermost.com. This vulnerability is known as CVE-2026-96259 since 09/22/2026. The exploitation appears to be easy. The attack can be launched remotely. Additional levels of successful authentication are necessary for exploitation. Neither technical details nor an exploit are publicly available.

Upgrading to version 11.7.11, 11.8.6, 11.9.2, 11.10.2 or 11.11.0 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: 4.1
VulDB Meta Temp Score: 4.0

VulDB Base Score: 2.7
VulDB Temp Score: 2.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 5.5
CNA Vector (Mattermost): 🔒

CVSSv2info

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

Exploitinginfo

Class: Server-side request forgery
CWE: CWE-918
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 11.7.11/11.8.6/11.9.2/11.10.2/11.11.0

Timelineinfo

09/22/2026 Advisory disclosed
09/22/2026 +0 days CVE reserved
09/22/2026 +0 days VulDB entry created
09/22/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: mattermost.com
Status: Confirmed

CVE: CVE-2026-96259 (🔒)
GCVE (CVE): GCVE-0-2026-96259
GCVE (VulDB): GCVE-100-408733

Entryinfo

Created: 09/22/2026 22:55
Changes: 09/22/2026 22:55 (63)
Complete: 🔍
Cache ID: 216::103

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