Security Advisory

CVE-2026-55517

CVE vulnerability detail - eXtreme Datacenter Security Operations

Published 2026-06-23 17:24:59
Last updated 2026-06-23 17:52:56
Assigner GitHub_M
CVSS score 4.3
State PUBLISHED

Description

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.