CVE-2026-64647

MEDIUMCVSS · not yet scored
—
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • No CVSS published and no exploitation signals yet
CISA-KEV: Not listedEPSS PROB: —CVSS v2: —Exploit: None knownExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

Next.js: Cache confusion of response bodies for requests with bodies containing invalid UTF-8 byte sequences

Impact

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.

Workarounds

If you cannot upgrade, consider only making fetch requests with UTF-8 bodies (default in Next.js). Applications using Pages Router are not vulnerable.

CVSS v3
—
EG Score
0.0(none)
EG Risk
0
EG Risk 0/100

EG Risk is EchelonGraph's 0–100 priority score. It fuses intrinsic severity with real-world exploitation and automatability, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. It is distinct from the 0–10 EG Score, which measures severity.

EPSS PROB
—
EPSS %ILE
—
KEV
Not listed

Published

July 22, 2026

Last Modified

July 22, 2026

Vendor Advisories for CVE-2026-64647(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
npm(1)
PackageVulnerable rangeFixed inDependents
next—16.2.11—

Data Freshness Timeline

(refreshed 2× in last 7d / 2× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-23 03:22 UTCEG score recompute
  2. 2026-07-22 23:22 UTCEG score recompute

Frequently asked(3)

What is CVE-2026-64647?
CVE-2026-64647 is a medium vulnerability published on July 22, 2026. Next.js: Cache confusion of response bodies for requests with bodies containing invalid UTF-8 byte sequences Impact 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…
When was CVE-2026-64647 disclosed?
CVE-2026-64647 was first published in the National Vulnerability Database on July 22, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
How do I remediate CVE-2026-64647?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-64647, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-64647

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