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Vulnerability · Published Jul 27, 2026 · Assigned by GitHub_M

CVE-2026-64648Next.js: Response Body Cache Confusion for Requests Containing Bodies

Medium 6.0

In plain English

A medium-severity security flaw in next.js from vercel. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 27% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)6.0Medium
Exploit odds (30 days)0.3%top 72.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

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 only applies to fetch calls with a request that has a different init than the one passed to fetch. A safe request would be: fetch(new Request(init), init). An unsafe request would be: fetch(new Request(init), aDifferentInit). This issue has been fixed in versions 15.5.21 and 16.2.11.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
npmnext15.5.21GHSA-68g3-v927-f742
npmnext16.2.11GHSA-68g3-v927-f742

Affected products (as reported)

VendorProductVersions
vercel next.js >= 13.0.0, < 15.5.21>= 16.0.0, < 16.2.11

Weakness: CWE-524 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N

References