CVE-2026-62389

Description

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.

References

https://www.vulncheck.com/advisories/ws-default-maxfragments-allows-memory-exhaustion-dos

https://github.com/websockets/ws/releases/tag/8.21.1

https://github.com/websockets/ws/issues/2331

https://github.com/websockets/ws/commit/f197ac65140920bdcecdab74bfc69c2d7858e55d

Details

Source: Mitre, NVD

Risk Information

CVSS v2

CVSS v3

CVSS v4