CVE-2026-53963
Discourse: Stored-XSS in 2FA delete confirmation modal
9.0
CRITICAL
CVSS 3.1
EPSS 0.45%
Description
Discourse is an open-source discussion platform. Prior to 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5, a malicious second factor name on an attacker-controlled account was not escaped in the delete confirmation dialog, allowing stored cross-site scripting when an administrator impersonated that account. This issue is fixed in versions 2026.6.0, 2026.5.1, 2026.4.2, and 2026.1.5.
How to fix CVE-2026-53963
To remediate CVE-2026-53963, upgrade the affected package to a fixed version below.
- —upgrade to 2026.1.5 or later
Is CVE-2026-53963 being exploited?
Low — EPSS is 0.5%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- >= 2026.1.0, < 2026.1.5, >= 2026.4.0, < 2026.4.2, >= 2026.5.0, < 2026.5.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | CRITICAL9.0 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H |