Vulnerability · Published Oct 26, 2026 · Assigned by Mattermost

CVE-2026-93848Mattermost OpenID discovery endpoint request bypasses outbound connection filtering, allowing SSRF by a System Administrator

Low 2.7

In plain English

A low-severity server-side request forgery in Mattermost from Mattermost. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 22% of all known vulnerabilities).

Severity (CVSS 3.1)2.7Low

Exploit odds (30 days)0.3%top 78.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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

Affected products (as reported)

Vendor	Product	Versions
Mattermost	Mattermost	11.7.0 – through 11.7.10

Weakness: CWE-918 · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:N

References

MMSA-2026-00774 vendor-advisory