CVE-2026-93848 PUBLISHED

Mattermost OpenID discovery endpoint request bypasses outbound connection filtering, allowing SSRF by a System Administrator

Assigner: Mattermost
Reserved: 18.09.2026 Published: 26.10.2026 Updated: 26.10.2026

Mattermost versions 11.7.x <= 11.7.10 fail to apply outbound internal-connection filtering to the OpenID discovery endpoint request which allows a System Administrator to determine whether internal addresses and ports are reachable from the server via an unauthenticated login request that triggers the discovery fetch.. Mattermost Advisory ID: MMSA-2026-00774

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N
CVSS Score: 2.7

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	Low
Privileges Required	High	Integrity Impact	None
User Interaction	None	Availability Impact	None

CVSS 3.1

Product Status

Vendor	Mattermost
Product	Mattermost
Versions	Default: unaffected affected from 11.7.0 to 11.7.10 (incl.) Version 11.11.0 is unaffected Version 11.7.11 is unaffected

Solutions

Update Mattermost to versions 11.11.0, 11.7.11 or higher.

Credits

gevakun finder

References

MMSA-2026-00774

Problem Types

CWE-918: Server-Side Request Forgery (SSRF) CWE