CVE-2026-48779: ws: Memory exhaustion DoS from tiny fragments and data chunks

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.4% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-06-17 · updated 2026-10-26
Weakness: CWE-400

Description

ws is an open source WebSocket client and server for Node.js. All versions from 1.1.0 up to (but not including) 5.2.5, from 6.0.0 up to 6.2.4, from 7.0.0 up to 7.5.11, and from 8.0.0 up to 8.21.0 are affected by a memory exhaustion DoS vulnerability. A peer can send a high volume of exceptionally small fragments and data chunks, with modest network traffic, to force the remote peer into allocating and holding structural wrappers that consume far more memory than the default documented message-size limit, leading to process termination due to OOM. This issue has been fixed in versions 5.2.5, 6.2.4, 7.5.11, and 8.21.0.

Affected products

websockets ws: from 1.1.0 before 5.2.5; from 6.0.0 before 6.2.4; from 7.0.0 before 7.5.11; from 8.0.0 before 8.21.0 — fixed in 5.2.5, 6.2.4, 7.5.11, 8.21.0
Npm Ws: from 1.1.0 before 5.2.5; from 6.0.0 before 6.2.4; from 7.0.0 before 7.5.11; from 8.0.0 before 8.21.0 — fixed in 5.2.5, 6.2.4, 7.5.11, 8.21.0

How to fix

Upgrade to a fixed version: websockets ws 5.2.5, 6.2.4, 7.5.11, 8.21.0; Npm Ws 5.2.5, 6.2.4, 7.5.11, 8.21.0. Check the vendor advisory for mitigations.

References

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