XSS in Discourse
CVE-2021-41095
Discourse is an open source discussion platform. There is a cross-site scripting (XSS) vulnerability in versions 2.7.7 and earlier of the `stable` branch, versions 2.8.0.beta6 and earlier of the `beta` branch, and versions 2.8.0.beta6 and earlier of the `tests-passed` branch. Rendering of some error messages that contain user input can be susceptible to XSS attacks. This vulnerability only affects sites which have blocked watched words that contain HTML tags, modified or disabled Discourse's default Content Security Policy. This issue is patched in the latest `stable`, `beta` and `tests-passed` versions of Discourse. As a workaround, avoid modifying or disabling Discourse’s default Content Security Policy, and blocking watched words containing HTML tags.
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.006 (44.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 4.2 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N.
Affected products
- Discourse — versions >= 2.8.0.beta1, <= 2.8.0.beta6, <= 2.7.7, 2.8.0
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Third Party Advisory)
- security-advisories@github.com (Patch, Third Party Advisory, x_refsource_MISC)
Frequently asked questions
- What is CVE-2021-41095?
- CVE-2021-41095 is a medium-severity vulnerability in Discourse, classified under Cross-site Scripting. CVSS score: 4.2/10. Published 2021-09-27.
- How severe is CVE-2021-41095?
- Medium severity. CVSS v3 base score is 4.2 out of 10.