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CVE-2025-27936

17
FAUCET Score

CVE-2025-27936 describes a timing attack vulnerability in Mattermost Plugin MSTeams versions prior to 2.1.0 and Mattermost Server versions 10.5.x up to 10.5.1 when the MS Teams plugin is enabled. This flaw allows an unauthenticated attacker to retrieve the MSTeams plugin's webhook secret due to a lack of constant-time comparison during secret validation. Rated Medium severity (CVSS 5.9), the attack requires high complexity but can lead to high confidentiality impact by exposing the webhook secret. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
< 10.5.2CPE matchmatch criteria
cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
< 2.1.0CPE matchmatch criteria
cpe:2.3:a:mattermost:ms_teams:*:*:*:*:*:*:*:*
>= 10.5.0, <= 10.5.1CPE match
cpe:2.3:a:mattermost:mattermost:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.3MEDIUM

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
Exploitability Score
1.6
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.32%
Probability of exploitation in next 30 days
EPSS Percentile
24.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0032 is in the 3rd percentile among its peer group of 19,958 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (3)

gopatch availablevia ghsa
Product: github.com/mattermost/mattermost/server/v8Fixed in: 10.5.2
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost-plugin-msteamsFixed in: 2.1.0
gopatch availablevia ghsa
Product: github.com/mattermost/mattermost/server/v8Fixed in: 8.0.0-20250314142426-c049748b8863

Vendor Advisories (1)

goGHSA-2j87-p623-8cc2medium

Mattermost vulnerable to Observable Timing Discrepancy

Apr 16, 2025

References

mattermost.com / security-updates
Vendor Advisory