REDHAT-BUG-2489980: High severity npm/undici vulnerability

Published Jun 17, 2026
·
Updated

Impact: The undici WebSocket client enforces maxPayloadSize on the cumulative byte count of fragments in a message but does not enforce a limit on the number of fragments. A malicious WebSocket server can stream many small or empty continuation frames that each pass per-frame and cumulative-size validation, collectively causing unbounded memory growth in the client process. The result is memory exhaustion and a denial of service.

Affected applications are those using the undici WebSocket client (new WebSocket(...)) or the WebSocketStream API that can be induced to connect to an attacker-controlled or compromised WebSocket endpoint.

All releases starting at undici 6.17.0 are affected.

Patches: Upgrade to undici >= 6.26.0, >= 7.28.0, or >= 8.5.0. Workarounds: No workaround is available. The fix must be applied through an upgrade.

Affected Software

4 affected components
npm/undici>=undefined
npm/undici<6.26.0
npm/undici<7.28.0
npm/undici<8.5.0

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade undici WebSocket client (undici) to a version that resolves this vulnerability.

    Fixed in 6.26.0
  2. Upgrade

    Upgrade undici WebSocket client (undici) to a version that resolves this vulnerability.

    Fixed in 7.28.0
  3. Upgrade

    Upgrade undici WebSocket client (undici) to a version that resolves this vulnerability.

    Fixed in 8.5.0

Event History

Jun 17, 2026
Data Sourced
via Red Hat·05:02 PM
DescriptionSeverityAffected Software
Free Weekly Intel

Don't miss critical vulnerabilities

Join thousands of security professionals who receive our weekly digest of trending CVEs, zero-days, and exploited vulnerabilities.

No spam. Unsubscribe anytime.

Frequently Asked Questions

1

What is the severity of REDHAT-BUG-2489980?

The severity of REDHAT-BUG-2489980 is classified as high with a score of 7.

2

What impact does REDHAT-BUG-2489980 have?

REDHAT-BUG-2489980 allows a malicious WebSocket server to potentially overload the client due to an unregulated number of fragments in a message.

3

How do I fix REDHAT-BUG-2489980?

To fix REDHAT-BUG-2489980, update the undici WebSocket client to the latest version where the vulnerability has been addressed.

4

What software is affected by REDHAT-BUG-2489980?

The vulnerable software affected by REDHAT-BUG-2489980 is npm/undici.

5

Can REDHAT-BUG-2489980 be exploited remotely?

Yes, REDHAT-BUG-2489980 can be exploited remotely by a malicious WebSocket server.

Contact

SecAlerts Pty Ltd.
132 Wickham Terrace
Fortitude Valley,
QLD 4006, Australia
info@secalerts.co
By using SecAlerts services, you agree to our services end-user license agreement. This website is safeguarded by reCAPTCHA and governed by the Google Privacy Policy and Terms of Service. All names, logos, and brands of products are owned by their respective owners, and any usage of these names, logos, and brands for identification purposes only does not imply endorsement. If you possess any content that requires removal, please get in touch with us.
© 2026 SecAlerts Pty Ltd.
ABN: 70 645 966 203, ACN: 645 966 203