CVE-2023-3672 is a high-severity (CVSS 7.3) Cross-site Scripting (XSS) vulnerability in webmention.js. 1 public exploit or proof-of-concept reference is indexed, so weaponization risk is real. A fix is available for webmention.js — see the affected versions and patch details below.
Cross-site Scripting (XSS) - DOM in plaidweb/webmention.js
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2023-3672.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
webmention.jsnpmDescription
Cross-site Scripting (XSS) - DOM in GitHub repository plaidweb/webmention.js prior to 0.5.5.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | webmention.js | all versions | 0.5.5npm install webmention.js@0.5.5 |
Affected Products
webmention.jsplaidwebResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for webmention.js, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update webmention.js to 0.5.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-3672 is resolved across your whole dependency graph.
Workarounds
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.
Frequently Asked Questions
Is CVE-2023-3672 in your dependencies?
Find it across npm, including transitive dependencies.