Description
Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, when a WebSocket connection was opened, 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.
Published: 2026-06-23
Score: 5.2 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Github GHSA Github GHSA GHSA-83pc-3rw9-qpwj Deno: WebSocket API sandbox bypass via missing post-DNS check
History

Wed, 24 Jun 2026 16:15:00 +0000

Type Values Removed Values Added
First Time appeared Deno
Deno deno
Vendors & Products Deno
Deno deno

Tue, 23 Jun 2026 19:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 23 Jun 2026 17:30:00 +0000

Type Values Removed Values Added
Description Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, when a WebSocket connection was opened, 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.
Title Deno: WebSocket API sandbox bypass via missing post-DNS check
Weaknesses CWE-918
References
Metrics cvssV3_1

{'score': 5.2, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N'}


cve-icon MITRE

Status: PUBLISHED

Assigner: GitHub_M

Published:

Updated: 2026-06-23T17:37:07.624Z

Reserved: 2026-06-01T22:03:19.640Z

Link: CVE-2026-49860

cve-icon Vulnrichment

Updated: 2026-06-23T17:37:04.101Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-06-24T16:00:06Z

Weaknesses