PT-2021-23945 · Vercel · Next.Js

Timneutkens

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Published

2021-12-07

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Updated

2026-05-18

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CVE-2021-43803

CVSS v3.1

7.5

High

VectorAV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Name of the Vulnerable Software and Affected Versions: Next.js versions prior to 12.0.5 Next.js versions prior to 11.1.3
Description: The issue arises when invalid or malformed URLs are processed, potentially leading to a server crash. This can occur in deployments using Next.js versions above 11.1.0 and below 12.0.5, Node.js above 15.0.0, and next start or a custom server. However, deployments on Vercel and similar environments where invalid requests are filtered before reaching Next.js are not affected.
Recommendations: For Next.js versions prior to 12.0.5, update to version 12.0.5 or later to resolve the issue. For Next.js versions prior to 11.1.3, update to version 11.1.3 or later to resolve the issue. As a temporary workaround, consider restricting access to the server or implementing filtering for invalid requests to minimize the risk of exploitation.

Fix

RCE

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Weakness Enumeration

Related Identifiers

CLEANSTART-2026-BD71263
CLEANSTART-2026-IS74202
CLEANSTART-2026-JR35772
CLEANSTART-2026-JY06700
CLEANSTART-2026-KN34553
CLEANSTART-2026-KZ45320
CLEANSTART-2026-LJ44720
CLEANSTART-2026-LN12820
CLEANSTART-2026-TX00223
CLEANSTART-2026-WI75198
CVE-2021-43803
GHSA-25MP-G6FV-MQXX

Affected Products

Next.Js