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CVE-2026-64647

MEDIUM
6.3
CVSS 4.0
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 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.

Metadata

CVE ID
CVE-2026-64647
State
PUBLISHED
Assigner
GitHub_M
Reserved
2026-07-20 17:11 UTC
Published
2026-07-27 19:11 UTC
Last updated
2026-07-27 19:27 UTC
Primary CWE
CWE-116
CWE-116: Improper Encoding or Escaping of Output
Vendor / Product
vercel / next.js
Sources
cve.org  ·  NVD

Severity & Metrics

6.3 MEDIUM CVSS 4.0
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
SSVC — CISA Coordinator
Exploitation
none
Automatable
no
Tech. Impact
partial
Affected products (1)
VendorProductPlatformVersions
vercel next.js — >= 13.0.0, < 15.5.21, >= 16.0.0, < 16.2.11
Weakness (CWE)
CWESourceDescription
CWE-116 cna CWE-116: Improper Encoding or Escaping of Output
CVSS scores (1)
ScoreSeverityVersionSourceVector
6.3 MEDIUM 4.0 cna CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
References (5)
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