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VulnerabilityPublished

CVE-2025-55070: Mattermost · Missing Authentication for Critical Functionality

Affects MattermostSource GCVE Database

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Not known to be exploited · CVSS 6.5 Medium : upgrade to 11 when convenient.

Data as of 13 Nov 2026, 18:45 UTC

CVSS 3.1 base score
6.5Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CNA (Mattermost)CVSS 3.16.5
Patch
Available – fixed in 11
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 Nov 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 13 Nov 2026.

What to do

Upgrade Mattermost to 11.

Affected software

ProductAffectedFixed in
Mattermost MattermostAffected
  • <11
Fixed in
  • 11

AI-suggested

Upgrade Mattermost to version 11 or later, where this vulnerability is fixed. No other mitigation is indicated or required according to the available data.

Description

CVE-2025-55070 is a vulnerability in Mattermost versions prior to 11 where multi-factor authentication is not enforced on WebSocket connections. This flaw allows unauthenticated users to access sensitive information through WebSocket events. The issue is addressed in Mattermost version 11.

References

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