PT-2026-50153 · Deno · Deno

7Thparkk + 1 · CVE-2026-49859 · Published 2026-06-16 · Updated 2026-06-23

Positive Technologies (AI Summary)

CVSS v3.1

5.2

Medium

Base vector

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

Name of the Vulnerable Software and Affected Versions Deno versions prior to 2.8.1

Description When the fetch() function is called, the runtime validates the destination hostname against --deny-net rules but fails to re-verify the IP addresses that the hostname resolves to. This allows an attacker-controlled script to use a specially crafted domain name that passes the initial hostname check but resolves to a denied IP address, effectively bypassing network isolation rules. This can lead to unauthorized access to blocked hosts, such as localhost or internal services, particularly when running untrusted or third-party code.

Recommendations Update to version 2.8.1. As a temporary mitigation, avoid granting --allow-net to untrusted code that relies on --deny-net restrictions for security.

Exploit

Fix

Protection Mechanism Failure

SSRF

Weakness Enumeration

CWE-693

CWE-918

Related Identifiers

CVE-2026-49859

GHSA-CPGJ-F7G3-2PP2

Affected Products

Deno

References · 6

• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49859.json · Exploit
• https://github.com/denoland/deno/security/advisories/GHSA-cpgj-f7g3-2pp2 · Vendor Advisory
• https://osv.dev/vulnerability/GHSA-cpgj-f7g3-2pp2 · Vendor Advisory
• https://osv.dev/vulnerability/CVE-2026-49859 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-49859 · Security Note
• https://github.com/denoland/deno · Note