medium5.2
CVE-2026-49859
Deno: `fetch()` API sandbox bypass via missing DNS resolution check
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| rust | deno | <= 2.8.0 | 2.8.1 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Deno | Deno | before 2.8.1 |