CVE-2021-43803
In versions of Next.js prior to 12.0.5 or 11.1.3, invalid or malformed URLs could lead to a server crash.
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 47.3%, higher than 99% of all known CVEs. Patch or mitigate before the next change window.
Description
Next.js is a React framework. In versions of Next.js prior to 12.0.5 or 11.1.3, invalid or malformed URLs could lead to a server crash. In order to be affected by this issue, the deployment must use 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. Deployments on Vercel are not affected, along with similar environments where invalid requests are filtered before reaching Next.js. Versions 12.0.5 and 11.1.3 contain patches for this issue.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 47.25% probability · 99th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-20
- Affected
- vercel/next.js
- Source
- security-advisories@github.com
EPSS moved from 47.3% on 2 October 2026 to 47.3% on 3 November 2026. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”.
References
- https://github.com/vercel/next.js/commit/6d98b4fb4315dec1badecf0e9bdc212a4272b264Patch, Third Party Advisory
- https://github.com/vercel/next.js/pull/32080Patch, Third Party Advisory
- https://github.com/vercel/next.js/releases/tag/v11.1.3Release Notes, Third Party Advisory
- https://github.com/vercel/next.js/releases/v12.0.5Release Notes, Third Party Advisory
- https://github.com/vercel/next.js/security/advisories/GHSA-25mp-g6fv-mqxxPatch, Third Party Advisory
- https://github.com/vercel/next.js/commit/6d98b4fb4315dec1badecf0e9bdc212a4272b264Patch, Third Party Advisory
- https://github.com/vercel/next.js/pull/32080Patch, Third Party Advisory
- https://github.com/vercel/next.js/releases/tag/v11.1.3Release Notes, Third Party Advisory
- https://github.com/vercel/next.js/releases/v12.0.5Release Notes, Third Party Advisory
- https://github.com/vercel/next.js/security/advisories/GHSA-25mp-g6fv-mqxxPatch, Third Party Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.