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Vulnerabilities

Vulnerability · CVE-2026-27977

Next.js is a React framework for building full-stack web applications.

Published Mar 18, 2026 · catalog updated Jun 17, 2026 · Next.js is a React

Check if you run it

No confirmed exploitation is on record for CVE-2026-27977. EPSS is 0.22%. Act only if a listed version of Next.js is a React is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (Next.js is a React).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Low2.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.22%
Remediation
Advisory link
Affected products
cpe vercel/next.js

Next.js is a React framework for building full-stack web applications. Starting in version 16.0.1 and prior to version 16.1.7, in , cross-site protection for internal websocket endpoints could treat as a bypass case even if is configured, allowing privacy-sensitive/opaque contexts (for example sandboxed documents) to connect unexpectedly. If a dev server is reachable from attacker-controlled content, an attacker may be able to connect to the HMR websocket channel and interact with dev websocket traffic. This affects development mode only. Apps without a configured still allow connections from any origin. The issue is fixed in version 16.1.7 by validating through the same cross-site origin-allowance checks used for other origins. If upgrading is not immediately possible, do not expose to untrusted networks and/or block websocket upgrades to when is at the proxy.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe vercel/next.jsversion unspecified

How to fix CVE-2026-27977

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-27977. EPSS is 0.22%. Act only if a listed version of Next.js is a React is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-1385. EPSS 0.22%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 18, 2026 · NIST NVD

    Detected

    Next.js is a React framework for building full-stack web applications. Starting in version 16.0.1 and prior to version 16.1.7, in , cross-site protection for internal websocket endpoints could treat as a bypass case even if is configured, allowing privacy-sensitive/opaque contexts (for example sandboxed documents) to connect unexpectedly. If a dev server is reachable from attacker-controlled conte

  2. Jun 17, 2026 · NIST NVD

    Updated

    Next.js is a React framework for building full-stack web applications. Starting in version 16.0.1 and prior to version 16.1.7, in , cross-site protection for internal websocket endpoints could treat as a bypass case even if is configured, allowing privacy-sensitive/opaque contexts (for example sandboxed documents) to connect unexpectedly. If a dev server is reachable from attacker-controlled conte

Sources

  • CVE.orgVulnerability recordCVE-2026-27977

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-27977

    30-day exploitation probability 0.2%

    first.org
  • NIST NVDVulnerability recordCVE-2026-27977

    Next.js is a React framework for building full-stack web applications. Starting in version 16.0.1 and prior to version 16.1.7, in , cross-site protection for internal websocket endpoints could treat as a bypass case even if is configur

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.