CVE-2026-54466

criticalcovered by 2 sourcesfirst seen 2026-07-15

Impact The frame format in draft versions of the WebSocket protocol includes a length header that allows an arbitrarily large integer to be encoded as a sequence of bytes with the high bit set. By sending an indefinite sequence of bytes with values 0x80 or above, a client can make the server parse these bytes into an ever-growing integer. Since JavaScript numbers are 64-bit floating point values, this number will eventually lose precision and lead to the subsequent payload being parsed incorrectly. Patches The issue has been patched in version 0.7.5 by rejecting the message if the length header exceeds the configured maximum message length. All users should upgrade to this version. Workarounds No known workarounds exist. Acknowledgements This issue was discovered and reported by Pranjali Thakur, DepthFirst Security Research Team.

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Exploitation outlook

Low exploitation risk0.26% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 18% of all EPSS-scored CVEs.

Advisory coverage (2)

unknownCVE-2026-54466: websocket-driver is a WebSocket protocol handler with pluggable I/O. Prior to 0.7.5, the frame…nvd · 2026-07-17
criticalGHSA-xv26-6w52-cph6: websocket-driver: Message corruption via abuse of protocol length headersghsa · 2026-07-15

External references

NVD record for CVE-2026-54466

CVE.org record

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