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UK Cyber Defence
VulnerabilityDeferred

CVE-2026-54490

websocket-driver is a WebSocket protocol handler with pluggable I/O.

MEDIUM 6.3EPSS 0.45%

Does this matter?

Lower severity and a low EPSS score (0.45%). Track it; it rarely justifies an emergency change on its own.

Description

websocket-driver is a WebSocket protocol handler with pluggable I/O. Prior to 0.7.5, if this library is used with the permessage-deflate extension, a WebSocket server or client can be made to accept messages that are larger than the configured maximum message size because the limit is checked against the message frames' length headers, which give the size of the compressed data, not the size after decompression in lib/websocket/driver/hybi.js. This can lead to applications accepting larger messages than expected and exceeding their intended resource usage. This issue is fixed in version 0.7.5.

CVSS 4.0
6.3 MEDIUMCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
EPSS
0.45% probability · 38th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-770
Source
security-advisories@github.com
EPSS trend
0%3%5%26 October 2026: 0.45%26 October 202626 October 2026

EPSS 0.4% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.