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Vulnerability record · CVE-2026-53963 · published 9 July 2026

CVE-2026-53963: Discourse cross-site scripting vulnerability

Discourse · Discourse

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.

9.0 CVSS 3.1 Critical EPSS 0.74% · top 47.4% CWE-79 · Cross-site scripting
9.0CVSS 3.1 base score
0.74%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
9References
14 Jul 2026Last modified by NVD

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.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/discourse/discourse/commit/40de62cddadc65c328a1028ab999f3fa94adbfed Patch
https://github.com/discourse/discourse/commit/529e17d4d570a48972e7cf64720e5dd1fdf23ca8 Patch
https://github.com/discourse/discourse/commit/d92973e51a46cf6dd20c71e6068e6769b67eea5b Patch
https://github.com/discourse/discourse/commit/daea5214d833eacbdd3b1a78d99eb14e9cabd915 Patch
https://github.com/discourse/discourse/releases/tag/v2026.1.5 Release Notes
https://github.com/discourse/discourse/releases/tag/v2026.4.2 Release Notes
https://github.com/discourse/discourse/releases/tag/v2026.5.1 Release Notes
https://github.com/discourse/discourse/releases/tag/v2026.6.0 Release Notes
https://github.com/discourse/discourse/security/advisories/GHSA-wg5x-7f23-m3r5 MitigationVendor Advisory

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Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-53963), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.