CVE-2026-49860
MediumCVSS 5.2Exploitation Probability (EPSS)
Low risk1th percentile — higher than 1% of all known CVEs
Summary
In Deno prior to 2.8.1, when a WebSocket connection was opened, only the destination hostname was checked against --deny-net rules, but the IP addresses that hostname resolved to were not re-checked. 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.
Risk Assessment
The organization is at risk of network security policy bypass, allowing a malicious script to communicate with internal or restricted resources, potentially leading to data exfiltration or further system compromise.
Recommendation
Immediately update Deno to version 2.8.1 or later, which contains the fix for this vulnerability.
Original NVD description (English source)
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.