CVE-2026-64647
Published:July 27, 2026
Updated:August 04, 2026
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.
Affected Packages
https://github.com/vercel/next.js.git (GITHUB):
Affected version(s) >=v16.0.0 <v16.2.11Fix Suggestion:
Update to version v16.2.11https://github.com/vercel/next.js.git (GITHUB):
Affected version(s) >=v13.0.0 <v15.5.21Fix Suggestion:
Update to version v15.5.21next (NPM):
Affected version(s) >=13.0.0 <15.5.21Fix Suggestion:
Update to version 15.5.21next (NPM):
Affected version(s) >=16.0.0 <16.2.11Fix Suggestion:
Update to version 16.2.11Related Resources (8)
Do you need more information?
Contact UsCVSS v4
Base Score:
6.3
Attack Vector
NETWORK
Attack Complexity
HIGH
Attack Requirements
PRESENT
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
LOW
Vulnerable System Integrity
LOW
Vulnerable System Availability
NONE
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
4.8
Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
LOW
Availability
NONE
Weakness Type (CWE)
Improper Encoding or Escaping of Output
EPSS
Base Score:
0.34