CVE-2026-49860 | Deno is a JavaScript, TypeScript, and WebAssembly runtime. P… | CVSS 5.2 MEDIUM

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.

Metadata

CVE ID: CVE-2026-49860
State: PUBLISHED
Assigner: GitHub_M
Reserved: 2026-06-01 22:03 UTC
Published: 2026-06-23 17:15 UTC
Last updated: 2026-06-23 17:37 UTC
Primary CWE: CWE-918
CWE-918: Server-Side Request Forgery (SSRF)
Vendor / Product: denoland / deno
Sources: cve.org · NVD

Severity & Metrics

5.2 MEDIUM CVSS 3.1

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

SSVC — CISA Coordinator

Exploitation: none
Automatable: no
Tech. Impact: partial

Affected products (1)

Vendor	Product	Platform	Versions
denoland	deno	—	< 2.8.1

Weakness (CWE)

CWE	Source	Description
CWE-918	cna	CWE-918: Server-Side Request Forgery (SSRF)

CVSS scores (1)

Score	Severity	Version	Source	Vector
5.2	MEDIUM	3.1	cna	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N

References (1)

https://github.com/denoland/deno/security/advisories/GHSA-83pc-3rw9-qpwj https://github.com/denoland/deno/security/advisories/GHSA-83pc-3rw9-qpwj