CVE-2026-59830

5.4 MEDIUMpublic exploit available

Published 2026-09-21 · Updated 2026-09-23

AI risk analysis

Summary: The flaw allows user-controlled display names to contain HTML, enabling script injection in post actions. This can lead to cross-site scripting (XSS) attacks.
Exploitability: Exploitation requires a user to choose a crafted display name and view another user's activity stream; not easily automated.
Blast radius: Real-world impact could include unauthorized script execution in users' browsers, potentially leading to data theft or further exploitation.
Prioritized remediation: Update to Discourse version 2026.7.0 immediately to mitigate the vulnerability.

xsshtml-injectiondiscourseweb

Analysis generated locally by qwen2.5:7b-instruct (no data left the box). AI-assisted — verify against primary sources before acting.

NVD description

Discourse is an open-source discussion platform. Prior to 2026.7.0, the post action component failed to escape user-controlled display names before interpolating them into an HTML string passed to trustHTML. A user who could choose a crafted display name could persist markup in post action descriptions. Viewing the affected user activity streams could execute attacker-controlled script in another user's browser. This issue is fixed in version 2026.7.0.

CVSS vector

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

Weaknesses

CWE-79

Public exploit & PoC references

References

Data: NVD (public domain). Analysis: local $0 model. Defensive use only.