Vulnerability in Vercel Next.js

CVE-2022-21721

Next.js is a React framework. Starting with version 12.0.0 and prior to version 12.0.9, vulnerable code could allow a bad actor to trigger a denial of service attack for anyone using i18n functionality. In order to be affected by this CVE, one must use next start or a custom server and the built-in i18n support. Deployments on Vercel, along with similar environments where invalid requests are filtered before reaching Next.js, are not affected. A patch has been released, `next@12.0.9`, that mitigates this issue. As a workaround, one may ensure `/${locale}/_next/` is blocked from reaching the Next.js instance until it becomes feasible to upgrade.

EPSS: 0.022 (80.3th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2022-21721?
CVE-2022-21721 is a medium-severity vulnerability in Vercel Next.js. CVSS score: 5.9/10. Published 2022-01-28.
How severe is CVE-2022-21721?
Medium severity. CVSS v3 base score is 5.9 out of 10.
Is CVE-2022-21721 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.