TI-2026-80425 Aliases CVE-2026-93848 GHSA-wfp9-hhgh-rm6p

Server-side request forgery in Mattermost OpenID discovery endpoint

LOW 13CWE-918Published 2026-10-26 · Updated 2026-10-26

Key facts

Attack vector: Network
Privileges required: High
User interaction: None
Attack complexity: Low
Impact type: Information disclosure
Confidentiality · integrity · availability: Low · None · None
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-918 and the CVSS impact.

Summary

Mattermost from 11.7.0 through 11.7.10 fails to apply outbound internal-connection filtering to the OpenID discovery endpoint request (CWE-918). A System Administrator can send an unauthenticated login request that triggers the discovery fetch and learn whether internal addresses and ports are reachable from the server.

Written with Claude Haiku 5.5 from the sources below · 2026-11-05

Description from the CNA

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

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV

EPSS 0.00289 21st percentileScored 2026-11-07

Fix Fixed Mattermost (Mattermost): 11.11.0, 11.7.11

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: None
Automatable: No
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
Mattermost	Mattermost	11.7.0 – 11.7.10	11.11.0, 11.7.11	Patch available	CNA

Mattermost VendorMattermost Affected 11.7.0 – 11.7.10 Fixed in 11.11.0, 11.7.11 Patch available CNA

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:mattermost:mattermost_server::::::::	11.7.0 to before 11.7.11	Vulnerable	Mattermost

cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:* Versions 11.7.0 to before 11.7.11 Vulnerable ·Mattermost

Remediation

Fixed versions are Mattermost 11.7.11 and 11.11.0, as listed in Mattermost advisory MMSA-2026-00774.

Written with Claude Haiku 5.5 from the sources below · 2026-11-05

Fix · CNA Mattermost (Mattermost) Fixed in 11.11.0, 11.7.11

Timeline

2026-10-26 Threatist record created from CVE-2026-93848
2026-10-26 CISA SSVC decision points changed
2026-10-27 Alias added: GHSA-wfp9-hhgh-rm6p

References

Advisory 1

MMSA-2026-00774

TI-2025-18933 Arbitrary file read in Mattermost Boards via import & export board archive CVSS 3.1CRITICAL 9.9
TI-2025-04465 Path Traversal Leading to RCE by Any Authenticated Mattermost User CVSS 3.1CRITICAL 9.9
TI-2017-14068 An issue was discovered in Mattermost Server before 3.6.2. CVSS 3.1CRITICAL 9.8
TI-2017-14060 An issue was discovered in Mattermost Server before 3.8.2, 3.7.5, and 3.6.7. CVSS 3.1CRITICAL 9.8
TI-2017-14048 An issue was discovered in Mattermost Server before 4.1.0, 4.0.4, and 3.10.3. CVSS 3.1CRITICAL 9.8
TI-2025-14360 Arbitrary file read via block duplication in Mattermost Boards CVSS 3.1CRITICAL 9.9

See all 505 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences