cvedb.io
CVE-2026-55517
MEDIUM · CVSS 4.3
EPSS exploitation probability: 0%
Published 2026-06-23T18:18:09.787 · Last modified 2026-06-29T13:27:11.020

Summary

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.7.5, a Deno program that opens a client WebSocket connection could be crashed by the remote server. While handling the WebSocket handshake response, Deno parsed the Sec-WebSocket-Protocol and Sec-WebSocket-Extensions response headers in a way that assumed their bytes were always printable ASCII. A response header containing non-visible-ASCII bytes (0x80-0xFF) caused a panic that aborted the entire Deno process. This vulnerability is fixed in 2.7.5.

Affected products

deno — deno

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.