{"id":"GHSA-83pc-3rw9-qpwj","summary":"Deno: WebSocket API sandbox bypass via missing post-DNS check","details":"## Summary\n\nWhen a WebSocket connection was opened, Deno checked the destination hostname\nagainst `--deny-net` rules but did not re-check the IP addresses that hostname\nresolved to. An attacker-controlled script could use a specially crafted domain\nname that passes the hostname check yet resolves to a denied IP, bypassing the\nnetwork restriction entirely.\n\n## Impact\n\nCode running under `--deny-net` could connect to hosts that the user intended\nto block. In practice this means network isolation rules — for example,\nblocking access to `localhost` or internal services — could be silently\ncircumvented by a malicious or compromised dependency.\n\n`Deno.connect` and `fetch()` were not affected by this specific issue (a\ncompanion advisory covers `fetch()`).\n\n## Who is affected\n\nUsers who:\n\n- run untrusted or third-party code with `deno run`, and\n- rely on `--deny-net` to restrict which hosts that code can reach.\n\nIf you do not use `--deny-net`, or if you only run fully trusted code, you are\nnot affected.\n\n## Workaround\n\nNo workaround is available short of upgrading. If upgrading immediately is not\npossible, avoid granting `--allow-net` to untrusted code that also has\n`--deny-net` restrictions you depend on for security.","aliases":["CVE-2026-49860"],"modified":"2026-07-20T21:15:27.253627173Z","published":"2026-06-16T19:04:07Z","database_specific":{"nvd_published_at":"2026-06-23T18:18:04Z","cwe_ids":["CWE-918"],"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-06-16T19:04:07Z"},"references":[{"type":"WEB","url":"https://github.com/denoland/deno/security/advisories/GHSA-83pc-3rw9-qpwj"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49860"},{"type":"PACKAGE","url":"https://github.com/denoland/deno"}],"affected":[{"package":{"name":"deno","ecosystem":"crates.io","purl":"pkg:cargo/deno"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.8.1"}]}],"database_specific":{"last_known_affected_version_range":"\u003c= 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"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N"}]}