CVE-2026-49860

Name: CVE-2026-49860
Creator: NVD / NIST
Published: 2026-06-23T18:18:04.053+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.2/10EPSS 0.11%

Last modified Jun 23, 2026

CVE-2026-49860 is a medium-severity vulnerability rated 5.2/10 on the CVSS scale. 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. EPSS estimates a 0.11% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

5.2/10

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

EPSS Probability

0.11%

1.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-918

References

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

Timeline

Published: Jun 23, 2026
Last Modified: Jun 23, 2026
Status: Undergoing Analysis

Frequently Asked Questions

What is CVE-2026-49860?

How severe is CVE-2026-49860?

CVE-2026-49860 has a CVSS score of 5.2/10 (MEDIUM severity). The EPSS model estimates a 0.11% probability of exploitation in the next 30 days.

How do I fix CVE-2026-49860?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-49860?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST