Vulnerability in Discourse Discourse-Footnote
CVE-2021-43827
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.008 (55.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 55th percentile — 55.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.008 · newest: 0.008 · change: 0.000
Affected products
- Discourse Discourse-Footnote — versions < 0.2
- Discourse Footnote
Weakness classification (CWE)
References
- github.com/discourse/discourse-footnote/security/advisories/GHSA-58vr-c56v-qr57 (Third Party Advisory)
- github.com/discourse/discourse-footnote/commit/796617e0131277011207541313522cd1… (Patch, Third Party Advisory)
Frequently asked questions
- What is CVE-2021-43827?
- CVE-2021-43827 is a medium-severity vulnerability in Discourse Discourse-Footnote, classified under Improper Handling of Exceptional Conditions. CVSS score: 4.3/10. Published 2021-12-14.
- How severe is CVE-2021-43827?
- Medium severity. CVSS v3 base score is 4.3 out of 10.