CVE-2026-6333
LowWhat is 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 slash command responses to an attacker-controlled server via a spoofed Host header.. Mattermost Advisory ID: MMSA-2026-00582
CVSS Vector Breakdown
CVSS 3.1Exploitable remotely over the network without requiring access to the local system.
Exploit requires specific conditions, timing, or configuration to succeed.
Basic user account required (e.g. standard login without admin rights).
No user interaction required. Exploit runs without any victim action.
Exploiting the vulnerability can affect other components beyond the vulnerable one.
No confidentiality impact. Sensitive data is not exposed.
Attacker can modify some data, but scope or consequence is limited.
No availability impact. Service remains fully operational.
FAQ
CVE-2026-6333 has a CVSS score of 3.5/10, rated as Low. Review the affected products list and apply vendor patches.
CVSS (Common Vulnerability Scoring System) rates vulnerability severity from 0.0 to 10.0. CVE-2026-6333 scores 3.5/10 (Low). Scores 9.0–10.0 are Critical, 7.0–8.9 are High, 4.0–6.9 are Medium, and below 4.0 are Low.
The list of devices confirmed to be affected by CVE-2026-6333 is shown in the "Affected Devices" section above. Check your firmware version against the vendor security advisory and apply the latest patch.
Apply the latest firmware or software update from the vendor. Check the References section above for official advisories and patch notes. If no patch is available, consider disabling the affected feature or isolating the device from untrusted networks.