GO-2025-4189 — Vulnetix

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GO-2025-4189 PUBLISHED CVSS 9.300000190734863 CRITICAL

Mattermost Server is vulnerable to XSS through author_link field in Slack attachments in github.com/mattermost/mattermost-server

Risk Scores

CVSS v4.0

9.300000190734863

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Affected Products

Vendor	Product	Versions
github.com	mattermost/mattermost-server	0, 4.2.0+incompatible, *

Timeline

Dec 8, 2025 CVE Published
Mar 3, 2026 CVE Updated
May 1, 2026 Security Advisory

References

https://github.com/advisories/GHSA-498j-wxww-j897 advisory
https://nvd.nist.gov/vuln/detail/CVE-2017-18879 advisory
https://mattermost.com/security-updates url

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