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
 

Affected Versions

undici: Red Hat Cryostat 4: Red Hat OpenShift Pipelines: Red Hat AMQ Broker 7: Red Hat Build of Podman Desktop: Red Hat Developer Hub: Red Hat Enterprise Linux 10: Red Hat Enterprise Linux 8: Red Hat Enterprise Linux 9: Red Hat Hardened Images: Red Hat OpenShift AI (RHOAI): Red Hat OpenShift Container Platform 4: Red Hat Openshift Data Foundation 4: Red Hat OpenShift Dev Spaces: Red Hat Self-service automation portal 2:

Exploit Probability

EPSS
0.28%
Percentile
19.97%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.