Mattermost versions 11.7.x <= 11.7.10 fail to apply outbound internal-connection filtering to the OpenID discovery
Source GCVE Database
Not known to be exploited · CVSS 2.7 Low.
Data as of 26 Oct 2026, 16:31 UTC
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:N/A:NExploitation evidence
Disclosed: evidence found.
CVE published 26 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| MattermostMattermost | Affected
| Fixed in– |
AI-suggested
Until a fix is available, restrict System Administrator access and monitor for updates from Mattermost regarding this issue.
Description
Mattermost versions 11.7.x up to 11.7.10 have a vulnerability where outbound internal-connection filtering is not applied to the OpenID discovery endpoint request. This flaw allows a System Administrator to determine if internal addresses and ports are reachable from the server by triggering an unauthenticated login request that initiates the discovery fetch. The issue is classified as low severity with a CVSS score of 2.7.