websockets ws up to 8.21.0 Receiver lib/receiver.js memory allocation

Summaryinfo

A vulnerability has been found in websockets ws up to 8.21.0 and classified as problematic. Affected by this issue is some unknown functionality of the file lib/receiver.js of the component Receiver. Performing a manipulation results in memory allocation. This vulnerability is reported as CVE-2026-62389. The attack is possible to be carried out remotely. No exploit exists.

Detailsinfo

A vulnerability was found in websockets ws up to 8.21.0. It has been classified as problematic. This affects an unknown part of the file lib/receiver.js of the component Receiver. The manipulation with an unknown input leads to a memory allocation vulnerability. CWE is classifying the issue as CWE-789. The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated. This is going to have an impact on availability. The summary by CVE is:

ws before 8.21.1 contains a memory exhaustion vulnerability in lib/receiver.js where the fragment guard only triggers when fragment count reaches maxFragments, allowing attackers to exhaust memory by sending incomplete fragmented WebSocket messages. Attackers can send a text frame with FIN=0 followed by continuation frames without completing the sequence, causing each fragment to be stored as a separate Buffer object with significant overhead, enabling denial of service through heap exhaustion.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-62389 since 07/14/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 8.21.1 eliminates this vulnerability.

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Productinfo

Vendor

• websockets

Name

• ws

Version

• 8.0
• 8.1
• 8.2
• 8.3
• 8.4
• 8.5
• 8.6
• 8.7
• 8.8
• 8.9
• 8.10
• 8.11
• 8.12
• 8.13
• 8.14
• 8.15
• 8.16
• 8.17
• 8.18
• 8.19
• 8.20
• 8.21.0

Website

• Product: https://github.com/websockets/ws/

CPE 2.3info

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CPE 2.2info

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