Home

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

PUBLISHED Reserved 2026-04-15 | Published 2026-05-18 | Updated 2026-05-18 | Assigner Mattermost




LOW: 3.5CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:N/I:L/A:N

Problem types

CWE-918: Server-Side Request Forgery (SSRF)

Product status

Default status
unaffected

11.5.0 (semver)
affected

10.11.0 (semver)
affected

11.6.0
unaffected

11.5.2
unaffected

10.11.14
unaffected

Credits

Juho Forsén finder

References

mattermost.com/security-updates (MMSA-2026-00582) vendor-advisory

cve.org (CVE-2026-6333)

nvd.nist.gov (CVE-2026-6333)

Download JSON