Vercel Next.js up to 15.5.20/16.2.10 Server-side Fetch Cache information disclosure

Summaryinfo

A vulnerability, which was classified as problematic, was found in Vercel Next.js up to 15.5.20/16.2.10. This impacts an unknown function of the component Server-side Fetch Cache. Such manipulation leads to information disclosure. This vulnerability is documented as CVE-2026-64647. The attack can be executed remotely. There is not any exploit available.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in Vercel Next.js up to 15.5.20/16.2.10. Affected by this issue is some unknown functionality of the component Server-side Fetch Cache. The manipulation with an unknown input leads to a information disclosure vulnerability. Using CWE to declare the problem leads to CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. Impacted is confidentiality. CVE summarizes:

Next.js is a React framework for building full-stack web applications. In versions 12.0.0 through 15.5.20 and 16.0.0 through 16.2.10, a server-side fetch with a request body may return a cached response body from a different request to the same URL but different body. Confidential data in the POST's response body would then leak to unauthorized requests. Though the request itself will not be deduped. This is only an issue when receiving request bodies with a content type charset other than UTF-8. For example, the UTF-16 byte sequences for 삃삃 and 섄섄 in the request body would share the same cache. This issue has been fixed in versions 15.5.21 and 16.2.11.

The advisory is available at github.com. This vulnerability is handled as CVE-2026-64647 since 07/20/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1592 by the MITRE ATT&CK project.

Upgrading to version 15.5.21 or 16.2.11 eliminates this vulnerability.

If you want to get best quality of vulnerability data, you may have to visit VulDB.

Productinfo

Type

• JavaScript Library

Vendor

• Vercel

Name

• Next.js

Version

• 15.5.0
• 15.5.1
• 15.5.2
• 15.5.3
• 15.5.4
• 15.5.5
• 15.5.6
• 15.5.7
• 15.5.8
• 15.5.9
• 15.5.10
• 15.5.11
• 15.5.12
• 15.5.13
• 15.5.14
• 15.5.15
• 15.5.16
• 15.5.17
• 15.5.18
• 15.5.19
• 15.5.20
• 16.2.0
• 16.2.1
• 16.2.2
• 16.2.3
• 16.2.4
• 16.2.5
• 16.2.6
• 16.2.7
• 16.2.8
• 16.2.9
• 16.2.10

Website

• Product: https://github.com/vercel/next.js/

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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