CVE-2026-49859
Deno: `fetch()` API sandbox bypass via missing DNS resolution check
- State
- Published
- Severity
- 5.2 Medium
- Published
- Jun 23, 2026
- Updated
- Jun 24, 2026
- Reserved
- Jun 1, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 5.2 Medium | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N | GitHub_M |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
denodenoland |
|
References
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