Undici WS Client Unbounded Fragment Size Causes DOS (v6.x8.x)
CVE-2026-12151 Published on June 17, 2026

undici WebSocket client vulnerable to denial of service via fragment count bypass
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.

NVD

Vulnerability Analysis

CVE-2026-12151 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.

Attack Vector:

NETWORK

Attack Complexity:

LOW

Privileges Required:

NONE

User Interaction:

NONE

Scope:

UNCHANGED

Confidentiality Impact:

NONE

Integrity Impact:

NONE

Availability Impact:

HIGH

Weakness Types

What is a Resource Exhaustion Vulnerability?

The software does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.

CVE-2026-12151 has been classified to as a Resource Exhaustion vulnerability or weakness.

Allocation of Resources Without Limits or Throttling

The software allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor.

Products Associated with CVE-2026-12151

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Red Hat Cryostat

Red Hat Openshift Pipelines

Red Hat Amq Broker

Red Hat Podman Desktop

Red Hat Rhdh

Red Hat Enterprise Linux (RHEL)

Red Hat Hummingbird

Red Hat Openshift Ai

Red Hat Openshift

Red Hat Openshift Data Foundation

Red Hat Openshift Devspaces

Red Hat Ansible Portal

Red Hat Cluster Observability Operator

Red Hat Enterprise Linux Eus

Red Hat Rhel Eus

Affected Versions

undici:

Before 6.26.0 is affected.
Version 6.26.0 is unaffected.
Version 7.0.0 and below 7.28.0 is affected.
Version 7.28.0 is unaffected.
Version 8.0.0 and below 8.5.0 is affected.
Version 8.5.0 is unaffected.

Red Hat Cryostat 4 on RHEL 9:

Version 4.2.0-13 and below * is unaffected.

Red Hat Enterprise Linux 10:

Version 1:24.18.0-1.el10_2 and below * is unaffected.

Red Hat Enterprise Linux 10:

Version 1:22.23.1-2.el10_2 and below * is unaffected.

Red Hat Enterprise Linux 10.0 Extended Update Support:

Version 1:22.23.1-2.el10_0 and below * is unaffected.

Red Hat Enterprise Linux 8:

Version 8100020260630152626.6d880403 and below * is unaffected.

Red Hat Enterprise Linux 8:

Version 8100020260703140402.6d880403 and below * is unaffected.

Red Hat Enterprise Linux 9:

Version 9080020260626074955.rhel9 and below * is unaffected.

Red Hat Enterprise Linux 9:

Version 9080020260626075442.rhel9 and below * is unaffected.

Red Hat Enterprise Linux 9.6 Extended Update Support:

Version 9060020260804140259.rhel9 and below * is unaffected.

Red Hat Cluster Observability Operator 1.5.0:

Version 1782840519 and below * is unaffected.

Red Hat Cluster Observability Operator 1.5.0:

Version 1782839981 and below * is unaffected.

Red Hat Cluster Observability Operator 1.5.0:

Version 1782839193 and below * is unaffected.

Red Hat Cluster Observability Operator 1.5.0:

Version 1782838753 and below * is unaffected.

Red Hat Cluster Observability Operator 1.5.0:

Version 1782839279 and below * is unaffected.

Red Hat Cluster Observability Operator 1.5.0:

Version 1782840539 and below * is unaffected.

Red Hat Cluster Observability Operator 1.5.0:

Version 1782841925 and below * is unaffected.

Red Hat Cluster Observability Operator 1.5.0:

Version 1782844225 and below * is unaffected.

Red Hat Cluster Observability Operator 1.5.0:

Version 1782839658 and below * is unaffected.

Red Hat Cluster Observability Operator 1.5.0:

Version 1782838476 and below * is unaffected.

Red Hat Cluster Observability Operator 1.5.0:

Version 1782839996 and below * is unaffected.

Red Hat Cluster Observability Operator 1.5.0:

Version 1782839494 and below * is unaffected.

Red Hat Developer Hub 1.10:

Version 1783448184 and below * is unaffected.

Red Hat Developer Hub 1.9:

Version 1784210921 and below * is unaffected.

Red Hat Hardened Images:

Version 26.5.0-1.3.hum1 and below * is unaffected.

Red Hat Hardened Images:

Version 24.18.0-0.3.hum1 and below * is unaffected.

Red Hat OpenShift Container Platform 4.16:

Version 1783306396 and below * is unaffected.

Red Hat OpenShift Container Platform 4.17:

Version 1784744859 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786705347 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786706101 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786705558 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786705646 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786706138 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786705741 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786705777 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786705802 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786705938 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786706577 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786706125 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786706177 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786706188 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786706679 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786706357 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786706612 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786706644 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786706659 and below * is unaffected.

Red Hat Openshift Data Foundation 4.18:

Version 1786706880 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786701839 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786701555 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786702052 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786702559 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786702713 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786702264 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786702448 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786702276 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786702440 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786702315 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786703071 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786702563 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786702636 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786702623 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786703137 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786702716 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786702872 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786702949 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786702917 and below * is unaffected.

Red Hat Openshift Data Foundation 4.19:

Version 1786703143 and below * is unaffected.