CVE-2026-49859
Deno: `fetch()` API sandbox bypass via missing DNS resolution check
CVSS Score
5.2
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-693 CWE-918 |
| Vendor | denoland |
| Product | deno |
| Published | Jun 23, 2026 |
Stay Ahead of the Next One
Get instant alerts for denoland deno
Be the first to know when new medium vulnerabilities affecting denoland deno are published — delivered to Slack, Telegram or Discord.
Get Free Alerts →
Free · No credit card · 60 sec setup
CVSS v3 Breakdown
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Changed
Confidentiality
Low
Integrity
Low
Availability
None
Affected Versions
denoland / deno
< 2.8.1