CVE-2026-49860 — Deno: WebSocket API sandbox bypass via missing post-DNS check
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, when a WebSocket connection was opened, Deno checked the destination hostname against --deny-net rules…
Published: 2026-06-23 · CVSS: 5.2 · CVSS 3.1
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, when a WebSocket connection was opened, Deno checked the destination hostname against --deny-net rules but did not re-check the IP addresses that hostname resolved to. An attacker-controlled script could use a specially crafted domain name that passes the hostname check yet resolves to a denied IP, bypassing the network restriction entirely. This vulnerability is fixed in 2.8.1.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7