Home/CVE/Discourse is an open source discussion platform. There is a cross-site scripting (XSS) vulnerability in versions 2.7.7 a
CVE

CVE-2021-41095

Discourse is an open source discussion platform. There is a cross-site scripting (XSS) vulnerability in versions 2.7.7 a

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.

MEDIUM · CVSS 4.2 EPSS 0.00224
Monitor
  • No active-exploitation, high-EPSS, or public-exploit signals - routine patching cadence
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
▤

Affected Products & Versions

2
discourse<= 2.7.7
discourseall versions
▣

Scoring & Timeline

4.2
MEDIUM · CVSS v3.1 · security-advisories@github.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD27 Sep 2021 · 08:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N
🔗

References & Sources

2
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://github.com/discourse/discourse/pull/14434/commits/40b776b9d39c41d9273d01eecf8fe03aa39fcb59PatchThird Party Advisory
https://github.com/discourse/discourse/security/advisories/GHSA-qvqx-2h7w-m479Third Party Advisory
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