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CVE-2021-43827

4.3 · MEDIUM

discourse-footnote is a library providing footnotes for posts in Discourse.

Published Dec 14, 2021CWE-755EPSS 0.83%

Overview

CVE-2021-43827 is a medium-severity vulnerability. It was published on December 14, 2021 and has a CVSS 3.1 base score of 4.3 (MEDIUM).

This vulnerability has a CVSS 3.1 base score of 4.3, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

Technical description

discourse-footnote is a library providing footnotes for posts in Discourse. ### Impact When posting an inline footnote wrapped in `<a>` tags (e.g. `<a>^[footnote]</a>`, the resulting rendered HTML would include a nested `<a>`, which is stripped by Nokogiri because it is not valid. This then caused a javascript error on topic pages because we were looking for an `<a>` element inside the footnote reference span and getting its ID, and because it did not exist we got a null reference error in javascript. Users are advised to update to version 0.2. As a workaround editing offending posts from the rails console or the database console for self-hosters, or disabling the plugin in the admin panel can mitigate this issue.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/discourse/discourse-footnote/commit/796617e0131277011207541313522cd1946661abGitHubgithub.com/discourse/discourse-footnote/security/advisories/GHSA-58vr-c56v-qr57GitHubgithub.com/discourse/discourse-footnote/commit/796617e0131277011207541313522cd1946661abGitHubgithub.com/discourse/discourse-footnote/security/advisories/GHSA-58vr-c56v-qr57

How CyberStrike helps

Frequently asked questions

What is CVE-2021-43827?

CVE-2021-43827 is a medium-severity vulnerability. It was published on December 14, 2021 and has a CVSS 3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2021-43827?

This vulnerability has a CVSS 3.1 base score of 4.3, rated MEDIUM. It can be exploited remotely over the network. Some level of privileges is required for exploitation.

How do I fix or remediate CVE-2021-43827?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-43827?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-43827 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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