Medium severity · published Feb 16, 2026
CVE-2026-1046
Arbitrary application execution via unvalidated server-controlled URLs in Help menu
6.5
CVSS
0.3%
EPSS
No
On KEV
Description
Mattermost Desktop App versions <=6.0 6.2.0 5.2.13.0 fail to validate help links which allows a malicious Mattermost server to execute arbitrary executables on a user’s system via the user clicking on certain items in the Help menu Mattermost Advisory ID: MMSA-2026-00577
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
Required
Confidentiality
None
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 17% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
MA
Mattermost · Mattermost
through 6.2.0; through 5.2.13 · source: vendor
MD
Mattermost Desktop · Mattermost
5.13.0 before 5.13.3; 6.0.0 before 6.0.3 · source: NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-1046
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-1046
Vendor Advisory
https://mattermost.com/security-updates
More from Mattermost
9.9
CVE-2026-4858
Path traversal in integration action URL leading to arbitrary API execution via system admin’s auth token.
9.6
CVE-2024-39777
Mattermost versions 9.9.x <= 9.9.0, 9.5.x <= 9.5.6, 9.7.x <= 9.7.5 and 9.8.x <= 9.8.1 fail to disallow unsolicited invites to expose access to local channels, when shared channels…
9.3
CVE-2026-12985
Mattermost DCR redirect URI allowlist bypass via improper URL component validation
9.1
CVE-2023-2193
Mattermost fails to invalidate existing authorization codes when deauthorizing an OAuth2 app, allowing an attacker possessing an authorization code to generate an access token
9.1
CVE-2019-20851
An issue was discovered in Mattermost Mobile Apps before 1.26.0