CVE-2021-32723
MEDIUMCVE-2021-32723 is a medium-severity (CVSS 6.5) Uncontrolled Resource Consumption vulnerability in prismjs. O3 Security confirms whether CVE-2021-32723 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Regular Expression Denial of Service (ReDoS) in Prism
Blast Radius
Weekly download volume for affected packages — a proxy for how broadly this vulnerability is deployed.
prismjsnpmDescription
Prism is a syntax highlighting library. Some languages before 1.24.0 are vulnerable to Regular Expression Denial of Service (ReDoS). When Prism is used to highlight untrusted (user-given) text, an attacker can craft a string that will take a very very long time to highlight. This problem has been fixed in Prism v1.24. As a workaround, do not use ASCIIDoc or ERB to highlight untrusted text. Other languages are not affected and can be used to highlight untrusted text.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | prismjs | all versions | 1.24.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for prismjs. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update prismjs to 1.24.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-32723 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2021-32723 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2021-32723. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2021-32723 in your dependencies?
O3 detects CVE-2021-32723 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.