CVE-2026-49859Published

Deno: `fetch()` API sandbox bypass via missing DNS resolution check

Exact source revision recorded 23 Oct 2026 15:48:27 UTC. It does not establish the source's current position. Latest evidence.

Recorded JSON

cve-program · CVE-2026-49859

Published

Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, when fetch() was called, 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 published: 23 Jun 2026 17:14:16 UTC
Source modified: 24 Jun 2026 14:23:09 UTC
Observed here: 23 Oct 2026 15:48:27 UTC
Source terms: CVE Program Terms of Use

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CVSS 3.1 · 5.2 CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N