{"id":"CVE-2026-63374","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-63374","generatedAt":"2026-10-28T00:59:45.516Z","title":"When a connection to a non-ASCII domain is hijacked or redirected, an attacker can obtain a legitimate certificate for the different ASCII hostname produced by IDNA 2003 and present it to the client, causing the malicious endpoint's certificate to…","description":"AnyIO is a high level asynchronous concurrency and networking framework that works on top of either Trio or asyncio. Prior to 4.14.2, connect_tcp() and TLSStream.wrap() can validate internationalized host names after the standard library converts them with IDNA 2003 instead of IDNA 2008. When a connection to a non-ASCII domain is hijacked or redirected, an attacker can obtain a legitimate certificate for the different ASCII hostname produced by IDNA 2003 and present it to the client, causing the malicious endpoint's certificate to validate. This issue is fixed in version 4.14.2.","published":"2026-09-22T16:17:51.000Z","lastModified":"2026-09-28T17:17:50.000Z","status":"Awaiting Analysis","sourceIdentifier":"security-advisories@github.com","cvss":{"version":"4.0","score":9.3,"severity":"CRITICAL","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M"},"cwe":["CWE-295","CWE-297"],"affected":[],"epss":{"score":0.00289,"percentile":0.21269,"date":"2026-10-26","history":[{"date":"2026-09-23","score":0.00306,"percentile":0.23545}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.29%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[{"kind":"new","label":"New CVE","at":"2026-09-22T16:17:51.000Z","detail":{"score":"9.3","severity":"CRITICAL","publishedAt":"2026-09-22T16:17:50.680Z"},"summary":"New CVE, critical severity (CVSS 9.3)."}],"references":[{"url":"https://github.com/agronholm/anyio/commit/68f58915f82d9be8109ebbbd8f5d70577d43f2ce","source":"security-advisories@github.com"},{"url":"https://github.com/agronholm/anyio/pull/1208","source":"security-advisories@github.com"},{"url":"https://github.com/agronholm/anyio/releases/tag/4.14.2","source":"security-advisories@github.com"},{"url":"https://github.com/agronholm/anyio/security/advisories/GHSA-82r6-8w77-94w6","source":"security-advisories@github.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-63374","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}