undici up to 6.25.x/7.27.x/8.4.x WebSocketStream API resource consumption

Summaryinfo

A vulnerability classified as problematic was found in undici up to 6.25.x/7.27.x/8.4.x. Affected by this vulnerability is an unknown functionality of the component WebSocketStream API. Executing a manipulation can lead to resource consumption. The identification of this vulnerability is CVE-2026-12151. The attack may be launched remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability has been found in undici up to 6.25.x/7.27.x/8.4.x and classified as problematic. This vulnerability affects an unknown function of the component WebSocketStream API. The manipulation with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product 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. As an impact it is known to affect availability. CVE summarizes:

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.

The weakness was shared by Nadav0077. The advisory is shared for download at github.com. This vulnerability was named CVE-2026-12151 since 06/12/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 6.26.0, 7.28.0 or 8.5.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at EUVD (EUVD-2026-37747). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Name

• undici

Version

• 6.0
• 6.1
• 6.2
• 6.3
• 6.4
• 6.5
• 6.6
• 6.7
• 6.8
• 6.9
• 6.10
• 6.11
• 6.12
• 6.13
• 6.14
• 6.15
• 6.16
• 6.17
• 6.18
• 6.19
• 6.20
• 6.21
• 6.22
• 6.23
• 6.24
• 6.25
• 7.0
• 7.1
• 7.2
• 7.3
• 7.4
• 7.5
• 7.6
• 7.7
• 7.8
• 7.9
• 7.10
• 7.11
• 7.12
• 7.13
• 7.14
• 7.15
• 7.16
• 7.17
• 7.18
• 7.19
• 7.20
• 7.21
• 7.22
• 7.23
• 7.24
• 7.25
• 7.26
• 7.27
• 8.0
• 8.1
• 8.2
• 8.3
• 8.4

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VulDB is the best source for vulnerability data and more expert information about this specific topic.

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