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LOW · 3.5

CVE-2026-6333

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect ...

Vulnerability Description

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect slash command responses to an attacker-controlled server via a spoofed Host header.. Mattermost Advisory ID: MMSA-2026-00582

CVSS Score

3.5

LOW

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:N
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
NONE
Scope
CHANGED
Confidentiality
NONE
Integrity
LOW
Availability
NONE

Affected Products

VendorProductVersions
MattermostMattermost Server>= 10.11.0, < 10.11.14

Related Weaknesses (CWE)

CWE-918

References

FAQ

What is CVE-2026-6333?

CVE-2026-6333 is a vulnerability with a CVSS score of 3.5 (LOW). Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13 fail to validate the Host header when constructing response URLs for custom slash commands which allows an authenticated attacker to redirect ...

How severe is CVE-2026-6333?

CVE-2026-6333 has been rated LOW with a CVSS base score of 3.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-6333?

Check the references section above for vendor advisories and patch information. Affected products include: Mattermost Mattermost Server.