CVE-2021-43827: Inline footnotes wrapped in <a> tags can cause errors in discourse-footnotes

First published: Tue Dec 14 2021(Updated: )

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.

Credit: security-advisories@github.com security-advisories@github.com

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• collector/nvd-index
• agent/references
• agent/type
• collector/mitre-cve
• source/MITRE
• agent/remedy
• agent/severity
• agent/weakness
• agent/title
• agent/first-publish-date
• agent/description
• collector/nvd-api
• source/NVD
• agent/software-canonical-lookup
• agent/last-modified-date
• agent/author
• agent/tags
• agent/softwarecombine
• agent/event
• vendor/discourse
• canonical/discourse discourse footnote