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Fencer Intel
high 7.5

CVE-2026-44573 json

Next.js: Middleware / Proxy bypass in Pages Router applications using i18n

published 6mo ago modified 14d ago also EUVD-2026-30057 , GHSA-36qx-fr4f-26g5

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.8%
EPSS 0.8% chance of exploitation in 30 days, percentile 56%
public exploits
0
none known

Summary

Next.js is a React framework for building full-stack web applications. From 12.2.0 to before 15.5.16 and 16.2.5, Applications using the Pages Router with i18n configured and middleware/proxy-based authorization can allow unauthorized access to protected page data through locale-less /_next/data/<buildId>/<page>.json requests. In affected configurations, middleware does not run for the unprefixed data route, allowing an attacker to retrieve SSR JSON for protected pages without passing the intended authorization checks. This vulnerability is fixed in 15.5.16 and 16.2.5.

Patch / fix

  • npm next 15.5.16, 16.2.5
  • Red Hat Red Hat Trusted Artifact Signer 1.3 1783958622
  • Red Hat Red Hat Trusted Artifact Signer 1.4 1783327185

Is CVE-2026-44573 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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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-2026-44573 updated cvss 7.5

next.js: Next.js: Information disclosure due to middleware bypass in Pages Router with i18n

  • 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
    affected: workaround, no fix planned “Will not fix”
  • Red Hat Trusted Artifact Signer 1.3 rhtas/rekor-search-ui-rhel9 1783958622
    fixed: vendor fix RHSA-2026:40974
  • Red Hat Trusted Artifact Signer 1.4 rhtas/rekor-search-ui-rhel9 1783327185
    fixed: vendor fix RHSA-2026:37272
  • Red Hat Streams for Apache Kafka 2.9.4
    fixed: vendor fix RHSA-2026:34608
  • Red Hat Streams for Apache Kafka 3.2.1
    fixed: vendor fix RHSA-2026:54435
  • Red Hat Enterprise Linux 7 firefox Red Hat Enterprise Linux 8 firefox, thunderbird Red Hat Enterprise Linux 9 firefox, firefox-x11, thunderbird Red Hat Enterprise Linux 10 firefox, thunderbird Red Hat Trusted Artifact Signer 1.3 rhtas/fulcio-rhel9 1783968972, rhtas/rekor-server-rhel9 1783969365, rhtas/trillian-redis-rhel9 1783411108, rhtas/trillian-database-rhel9 1783960127, rhtas/trillian-logserver-rhel9 1783968861, rhtas/trillian-logsigner-rhel9 1783968861, +3 more Red Hat Trusted Artifact Signer 1.4 rhtas/fulcio-rhel9 1783326847, rhtas/rekor-server-rhel9 1783332625, rhtas/trillian-redis-rhel9 1783329793, rhtas/trillian-database-rhel9 1783329793, rhtas/trillian-logserver-rhel9 1783329793, rhtas/trillian-logsigner-rhel9 1783329793, +3 more
    not affected: vulnerable code not present

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
5mo ago

Exploit prediction

0.80% chance of exploitation in the next 30 days, higher than 56% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
npm next
>=12.2.0, <15.5.16
>=16.0.0, <16.2.5
15.5.16
16.2.5

Affected products

  • vercel next.js
  • Red Hat Streams for Apache Kafka 2.9.4
  • Red Hat Red Hat Trusted Artifact Signer 1.3
  • Red Hat Red Hat Trusted Artifact Signer 1.4
  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 7
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Enterprise Linux AI (RHEL AI) 3
  • Red Hat streams for Apache Kafka 3

Classification

Weakness
  • CWE-863 Incorrect Authorization
  • CWE-551 Incorrect Behavior Order: Authorization Before Parsing and Canonicalization
Technology feeds

References

Sources

Fencer Intel 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.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.