CVE-2025-27936

Webhook Secret Exposure via Timing attack in MSteams plugin

Description

Mattermost Plugin MSTeams versions <2.1.0 and Mattermost Server versions 10.5.x <=10.5.1 with the MS Teams plugin enabled fail to perform constant time comparison on a MSTeams plugin webhook secret which allows an attacker to retrieve the webhook secret of the MSTeams plugin via a timing attack during webhook secret comparison.

Remediation

Solution:

  • Update Mattermost Plugin MSTeams to version 2.1.1 or Mattermost Server to versions 10.6.0, 10.5.2 or higher.

Category

5.3
CVSS
Severity: Medium
CVSS 3.1 •
EPSS 0.04%
Affected: Mattermost Mattermost
Published at:
Updated at:

References

Link Tags
https://mattermost.com/security-updates

Frequently Asked Questions

What is the severity of CVE-2025-27936?
CVE-2025-27936 has been scored as a medium severity vulnerability.
How to fix CVE-2025-27936?
To fix CVE-2025-27936: Update Mattermost Plugin MSTeams to version 2.1.1 or Mattermost Server to versions 10.6.0, 10.5.2 or higher.
Is CVE-2025-27936 being actively exploited in the wild?
As for now, there are no information to confirm that CVE-2025-27936 is being actively exploited. According to its EPSS score, there is a ~0% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2025-27936?
CVE-2025-27936 affects Mattermost Mattermost.
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