CVE-2026-12151
Received Received - Intake
Memory Exhaustion in Undici WebSocket Client

Publication date: 2026-06-17

Last updated on: 2026-06-17

Assigner: openjs

Description
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.
CVSS Scores
EPSS Scores
Probability:
Percentile:
Meta Information
Published
2026-06-17
Last Modified
2026-06-17
Generated
2026-06-17
AI Q&A
2026-06-17
EPSS Evaluated
N/A
NVD
CVE-2026-12151
EUVD
EUVD-2026-37747
Affected Vendors & Products
Showing 8 associated CPEs
Vendor Product Version / Range
undici undici From 6.17.0 (inc)
undici undici to 6.26.0 (exc)
undici undici to 7.28.0 (exc)
undici undici to 8.5.0 (exc)
nodejs undici From 6.17.0 (inc)
nodejs undici 6.26.0
nodejs undici 7.28.0
nodejs undici 8.5.0
Helpful Resources
Exploitability
CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-770 The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.
CWE-400 The product does not properly control the allocation and maintenance of a limited resource.
Attack-Flow Graph
AI Quick Actions
Instant insights powered by AI
Executive Summary

This vulnerability exists in the undici WebSocket client where it enforces a maximum payload size on the cumulative byte count of message fragments but does not limit the number of fragments. A malicious WebSocket server can exploit this by sending many small or empty continuation frames that individually pass validation but collectively cause unbounded memory growth in the client.

As a result, the client process can experience memory exhaustion, leading to a denial of service (DoS) condition.

Impact Analysis

If your application uses the undici WebSocket client or the WebSocketStream API to connect to WebSocket endpoints, an attacker controlling or compromising such an endpoint can exploit this vulnerability.

The impact is that the attacker can cause your client application to consume unbounded memory, leading to memory exhaustion and ultimately causing the application to crash or become unresponsive, resulting in a denial of service.

Mitigation Strategies

To mitigate this vulnerability, you should upgrade the undici WebSocket client to a patched version.

  • Upgrade to undici version 6.26.0 or later.
  • Alternatively, upgrade to undici version 7.28.0 or later.
  • Or upgrade to undici version 8.5.0 or later.

No workarounds are available; the fix requires applying the upgrade.

Compliance Impact

The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

Chat Assistant
Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-12151. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70
EPSS Chart