{"id":"CVE-2026-49859","aliases":["GHSA-cpgj-f7g3-2pp2"],"url":"https://o3.security/vulnerability/CVE-2026-49859","summary":"Deno: `fetch()` API sandbox bypass via missing DNS resolution check","details":"Deno is a JavaScript, TypeScript, and WebAssembly runtime. Prior to 2.8.1, when fetch() was called, 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.","published":"2026-06-23T17:14:16.888Z","modified":"2026-08-12T03:51:11.584974833Z","cvss":{"score":5.2,"severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N"},"epss":{"score":0.00141,"percentile":0.03718,"asOf":"2026-09-04"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"crates.io","name":"deno","fixedVersion":"2.8.1"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49859.json"},{"type":"ADVISORY","url":"https://github.com/denoland/deno/security/advisories/GHSA-cpgj-f7g3-2pp2"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-49859"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-12T03:51:11.584974833Z"}}