High severity · published Jun 19, 2020
CVE-2017-18886
An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2
8.8
CVSS
1%
EPSS
No
On KEV
Description
An issue was discovered in Mattermost Server before 4.3.0, 4.2.1, and 4.1.2. It allows a bypass of restrictions on use of slash commands.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)1.0% · higher than 61% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MS
Mattermost Server · Mattermost
before 4.1.2; 4.2.0 before 4.2.1; 4.3.0; 4.3.0; 4.3.0; 4.3.0 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2017-18886
CVE.org
https://www.cve.org/CVERecord?id=CVE-2017-18886
Vendor Advisory
https://mattermost.com/security-updates/
More from Mattermost Server
9.9
CVE-2026-4858
Path traversal in integration action URL leading to arbitrary API execution via system admin’s auth token.
9.9
CVE-2025-12421
Account Takeover via Code Exchange Endpoint
9.9
CVE-2025-12419
Account takeover on OAuth/OpenID-enabled servers
9.9
CVE-2025-4981
Mattermost versions 10.5.x <= 10.5.5, 9.11.x <= 9.11.15, 10.8.x <= 10.8.0, 10.7.x <= 10.7.2, 10.6.x <= 10.6.5 fail to sanitize filenames in the archive extractor which allows…
9.8
CVE-2023-6458
Mattermost webapp fails to validate route parameters in/<TEAM_NAME>/channels/<CHANNEL_NAME> allowing an attacker to perform a client-side path traversal
