CVE-2021-43827 is a vulnerability in Discourse Footnote
Published on December 14, 2021
Inline footnotes wrapped in <a> tags can cause errors in discourse-footnotes
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.
Vulnerability Analysis
CVE-2021-43827 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a small impact on availability.
Weakness Type
Improper Handling of Exceptional Conditions
The software does not handle or incorrectly handles an exceptional condition.
Products Associated with CVE-2021-43827
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Affected Versions
discourse-footnote Version < 0.2 is affected by CVE-2021-43827Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.