CVE-2026-53963
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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.73%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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
- 9.0 CRITICALCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
- EPSS
- 0.73% probability · 52th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-79
- Affected
- discourse/discourse
- Source
- security-advisories@github.com
References
- https://github.com/discourse/discourse/commit/40de62cddadc65c328a1028ab999f3fa94adbfedPatch
- https://github.com/discourse/discourse/commit/529e17d4d570a48972e7cf64720e5dd1fdf23ca8Patch
- https://github.com/discourse/discourse/commit/d92973e51a46cf6dd20c71e6068e6769b67eea5bPatch
- https://github.com/discourse/discourse/commit/daea5214d833eacbdd3b1a78d99eb14e9cabd915Patch
- https://github.com/discourse/discourse/releases/tag/v2026.1.5Release Notes
- https://github.com/discourse/discourse/releases/tag/v2026.4.2Release Notes
- https://github.com/discourse/discourse/releases/tag/v2026.5.1Release Notes
- https://github.com/discourse/discourse/releases/tag/v2026.6.0Release Notes
- https://github.com/discourse/discourse/security/advisories/GHSA-wg5x-7f23-m3r5Mitigation, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.