GHSA-83pc-3rw9-qpwj

Suggest an improvement
Source
https://github.com/advisories/GHSA-83pc-3rw9-qpwj
Import Source
https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-83pc-3rw9-qpwj/GHSA-83pc-3rw9-qpwj.json
JSON Data
https://api.osv.dev/v1/vulns/GHSA-83pc-3rw9-qpwj
Aliases
Downstream
Published
2026-06-16T19:04:07Z
Modified
2026-07-20T21:15:27Z
Severity
  • 5.2 (Medium) CVSS_V3 - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N CVSS Calculator
Summary
Deno: WebSocket API sandbox bypass via missing post-DNS check
Details

Summary

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.

Impact

Code running under --deny-net could connect to hosts that the user intended to block. In practice this means network isolation rules — for example, blocking access to localhost or internal services — could be silently circumvented by a malicious or compromised dependency.

Deno.connect and fetch() were not affected by this specific issue (a companion advisory covers fetch()).

Who is affected

Users who:

  • run untrusted or third-party code with deno run, and
  • rely on --deny-net to restrict which hosts that code can reach.

If you do not use --deny-net, or if you only run fully trusted code, you are not affected.

Workaround

No workaround is available short of upgrading. If upgrading immediately is not possible, avoid granting --allow-net to untrusted code that also has --deny-net restrictions you depend on for security.

Database specific 
{
    "cwe_ids": [
        "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-16T19:04:07Z",
    "nvd_published_at": "2026-06-23T18:18:04Z",
    "severity": "MODERATE"
}
References

Affected packages

crates.io / deno

Package

Name
deno
View open source insights on deps.dev
Purl
pkg:cargo/deno

Affected ranges

Type
SEMVER
Events
Introduced
0 Unknown introduced version / All previous versions are affected
Fixed
2.8.1

Database specific

last_known_affected_version_range 
"<= 2.8.0"
source 
"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/06/GHSA-83pc-3rw9-qpwj/GHSA-83pc-3rw9-qpwj.json"