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VulnerabilityPublished

Next.js Vulnerable to Denial of Service with Server Components

Affects nextSource GCVE Database

0

Mentioned vulnerabilities

CVSS 7.5 High : upgrade to 15.5.16 soon.

Data as of 27 Oct 2026, 00:43 UTC

CVSS 3.1 base score
7.5High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 15.5.16, 16.2.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

What to do

Upgrade next to 15.5.16; next to 16.2.5.

Affected software

ProductAffectedFixed in
npmnextAffected
  • >=13.0.0 <15.5.16
Fixed in
  • 15.5.16
npmnextAffected
  • >=16.0.0 <16.2.5
Fixed in
  • 16.2.5

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Apply the official patches by upgrading Next.js to version 15.5.16 or later for the 15.x branch, or 16.2.5 or later for the 16.x branch. These versions contain fixes that prevent the excessive CPU usage during deserialization. No other mitigation is specified or required.

Description

Certain React Server Components packages used by Next.js versions 13.x, 14.x, 15.x prior to 15.5.16, and 16.x prior to 16.2.5 with the App Router are vulnerable to a denial of service (DoS) attack. An attacker can send a specially crafted HTTP request to an App Router Server Function endpoint that triggers excessive CPU usage during deserialization, causing service disruption. This vulnerability is tracked as CVE-2026-23870 and has a high severity rating with a CVSS score of 7.5. Fixed versions 15.5.16 and 16.2.5 are available to mitigate the issue.

References

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