{"id":"CVE-2026-49859","state":"PUBLISHED","title":"Deno: `fetch()` API sandbox bypass via missing DNS resolution check","description":"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.","publishedAt":"2026-06-23T17:14:16.888Z","updatedAt":"2026-06-24T14:23:09.068Z","severity":{"score":5.2,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","source":"GitHub_M"},"assigner":"GitHub_M","products":["denoland deno"],"affected":[{"vendor":"denoland","product":"deno","versions":[{"version":"< 2.8.1","status":"affected"}]}],"references":["https://github.com/denoland/deno/security/advisories/GHSA-cpgj-f7g3-2pp2"],"weaknesses":["CWE-693","CWE-918"],"ingestedAt":"2026-10-29T20:12:07.131Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/49xxx/CVE-2026-49859.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-49859","state":"PUBLISHED","datePublished":"2026-06-23T17:14:16.888Z","dateUpdated":"2026-06-24T14:23:09.068Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-06-01T22:03:19.640Z"},"containers":{"cna":{"title":"Deno: `fetch()` API sandbox bypass via missing DNS resolution check","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"denoland","product":"deno","versions":[{"version":"< 2.8.1","status":"affected"}]}],"references":[{"url":"https://github.com/denoland/deno/security/advisories/GHSA-cpgj-f7g3-2pp2","name":"https://github.com/denoland/deno/security/advisories/GHSA-cpgj-f7g3-2pp2","tags":["x_refsource_CONFIRM"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"LOCAL","availabilityImpact":"NONE","baseScore":5.2,"baseSeverity":"MEDIUM","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"LOW","scope":"CHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-693","lang":"en","description":"CWE-693: Protection Mechanism Failure","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-918","lang":"en","description":"CWE-918: Server-Side Request Forgery (SSRF)","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-06-23T17:14:16.888Z"},"source":{"advisory":"GHSA-cpgj-f7g3-2pp2","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-06-24T14:22:56.623204Z","id":"CVE-2026-49859","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-06-24T14:23:09.068Z"}}]}}}