Vulnerability · Published Sep 27, 2021 · Assigned by GitHub_M

CVE-2021-41095XSS via blocked watched word in error message

Medium 4.2

In plain English

A medium-severity cross-site scripting in discourse from discourse. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 48% of all known vulnerabilities).

Severity (CVSS 3.1)4.2Medium
Exploit odds (30 days)0.6%top 51.9% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

VendorProductVersions
discourse discourse <= 2.7.7>= 2.8.0.beta1, <= 2.8.0.beta6

Weakness: CWE-79 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N

References