CVE-2026-49859
Medium
Description
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.
SeverityMedium
CVSS5.2
Exploit probability3. percentile0.1%
Product
Deno
PublishedJun 23, 2026
First seenJun 23, 2026
How to fix
Update
- deno deno2.8.1 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| deno deno | v < 2.8.1 | 2.8.1 |
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