Skip to content
Fencer Vulns
medium 5.3

CVE-2026-64643 json

Next.js: Unauthenticated Disclosure of Internal Server Function endpoints

published 2026-07-21 3 mo ago modified 2026-10-24 15 d ago also EUVD-2026-49383 , GHSA-955p-x3mx-jcvp

cvss
5.3
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 43%
public exploits
0
none known

Summary

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, Next.js applications using App Router, Server Actions (use server) or use cache endpoints can be disclosed bypassing any authentication on the pages where these endpoints are usually used. Server Action IDs can be disclosed to unauthenticated users via publicly served client artifacts (for example, static chunks containing action references). Affected users are applications using App Router and Server Actions. By itself, this disclosure is typically a recon/enumeration primitive; however, it can increase risk when combined with other weaknesses. This issue has been fixed in versions 15.5.21 and 16.2.11.

Patch / fix

  • npm next 15.5.21, 16.2.11
  • vercel next.js 15.5.21, 16.2.11

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-64643 updated cvss 5.3

next: Next.js: Information disclosure via Server Action ID exposure

  • Red Hat Enterprise Linux 7 firefox, firefox 140.12.0-1.el10_0 Red Hat Enterprise Linux 8 firefox, thunderbird, firefox 140.12.0-1.el10_0, thunderbird 140.12.0-1.el10_2 Red Hat Enterprise Linux 9 firefox, firefox-x11, thunderbird, firefox 140.12.0-1.el10_0, thunderbird 140.12.0-1.el10_2 Red Hat Enterprise Linux 10 firefox 140.12.0-1.el10_0, thunderbird 140.12.0-1.el10_2 Red Hat Enterprise Linux AI (RHEL AI) 3 rhelai3/bootc-cuda-rhel9, rhelai3/bootc-rocm-rhel9, rhelai3/bootc-gaudi-rhel9, rhelai3/disk-image-cuda-rhel9 Red Hat Trusted Artifact Signer rhtas/rekor-search-ui-rhel9
    +2 more products
    Red Hat streams for Apache Kafka 2 next 15.5.18 Red Hat streams for Apache Kafka 3 next 15.5.18
    affected: workaround, no fix available “Fix deferred”

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.51% chance of exploitation in the next 30 days, higher than 43% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
CNA 4.0 6.3 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Affected packages

ecosystem package affected fixed in
npm next
>=13.0.0, <15.5.21
>=16.0.0, <16.2.11
15.5.21
16.2.11

Affected products

  • vercel next.js

Classification

Weakness
  • CWE-201 Insertion of Sensitive Information Into Sent Data
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of vercel/next.js published their own advisory on GitHub. Reviewed sources take precedence over it.