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MEDIUM · 5.2

CVE-2026-49859

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...

Vulnerability 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.

CVSS Score

5.2

MEDIUM

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 Products

VendorProductVersions
DenoDeno< 2.8.1

Related Weaknesses (CWE)

CWE-918CWE-693

References

FAQ

What is CVE-2026-49859?

CVE-2026-49859 is a vulnerability with a CVSS score of 5.2 (MEDIUM). 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...

How severe is CVE-2026-49859?

CVE-2026-49859 has been rated MEDIUM with a CVSS base score of 5.2/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-49859?

Check the references section above for vendor advisories and patch information. Affected products include: Deno Deno.