Mattermost vulnerable to Observable Timing Discrepancy

CVE-2025-27936 → View on GitHub ↗ View on CVE.org ↗ View on NVD ↗

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.

Basic information

Type
reviewed
Severity
medium
Advisory on GitHub
Open advisory ↗
Repository advisory
—
Source code
Browse source ↗
Published (advisory)
2025-04-16 12:31:19 UTC
Updated
2025-04-23 15:18:39 UTC
GitHub reviewed
2025-04-16 14:58:55 UTC
NVD published
2025-04-16 10:15:14 UTC

EPSS Score

Score Percentile
0.21% 43.53%

CVSS Scores

Base score Version Severity Vector
5.3 3.1 —
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.

Identifiers

Type Value
GHSA GHSA-2j87-p623-8cc2 ↗
CVE CVE-2025-27936 ↗

CWEs

CWE id Name
CWE-208 Observable Timing Discrepancy

Affected packages (3)

Vulnerable version ranges and first patched releases as published by GitHub.

Ecosystem Package Vulnerable range First patched Vulnerable functions
go github.com/mattermost/mattermost/server/v8 >= 10.5.0, < 10.5.2 10.5.2 —
go github.com/mattermost/mattermost-plugin-msteams <= 1.15.0 2.1.0 —
go github.com/mattermost/mattermost/server/v8 < 8.0.0-20250314142426-c049748b8863 8.0.0-20250314142426-c049748b8863 —

References

cvelogic Threat Intelligence