CVE-2021-23413 is a medium-severity (CVSS 5.3) vulnerability in jszip. 3 public exploit references exist, so weaponization risk is real. A fix is available for jszip — see the affected versions and patch details below.
jszip Vulnerable to Prototype Pollution
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2021-23413 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 379,842 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
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.
jszipnpmDescription
This affects the package jszip before 3.7.0. Crafting a new zip file with filenames set to Object prototype values (e.g proto, toString, etc) results in a returned object with a modified prototype instance.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | jszip | ≥ 3.0.0&&< 3.7.0 | 3.7.0npm install jszip@3.7.0 |
| 📦npm | jszip | all versions | 2.7.0npm install jszip@2.7.0 |
Affected Products
jszipjszip_projectResearch 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 jszip, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update jszip to 3.7.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-23413 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.
Frequently Asked Questions
Is CVE-2021-23413 in your dependencies?
Find it across npm, including transitive dependencies.