{"id":"CVE-2026-44726","aliases":["GHSA-chqv-56wv-7564"],"url":"https://o3.security/vulnerability/CVE-2026-44726","summary":"Deno: TLS retry copies stale upgrade hook, risking plaintext traffic","details":"Deno is a JavaScript, TypeScript, and WebAssembly runtime. From 2.0.0 until 2.7.8, a flaw in Deno's Node.js tls compatibility layer could cause a TLS client to transmit application data in plaintext after a connection retry. When `autoSelectFamily was enabled and the first address-family attempt failed, the socket reinitialization path reused a stale TLS upgrade hook that was bound to the original, failed handle. As a result, the replacement TCP connection was never upgraded to TLS, and any data the application wrote before the secureConnect event travelled over the network unencrypted. A network attacker positioned to cause the initial connection attempt to fail (for example, by dropping IPv6 traffic on a dual-stack host) could deterministically trigger the fallback path and observe or tamper with traffic that the application believed was TLS-protected. This vulnerability is fixed in 2.7.8.","published":"2026-06-23T17:24:02.702Z","modified":"2026-08-07T11:31:12.736403827Z","cvss":{"score":7.4,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N"},"epss":{"score":0.00169,"percentile":0.06521,"asOf":"2026-08-09"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"crates.io","name":"deno","fixedVersion":"2.7.8"}],"fix":null,"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/44xxx/CVE-2026-44726.json"},{"type":"ADVISORY","url":"https://github.com/denoland/deno/security/advisories/GHSA-chqv-56wv-7564"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-44726"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-07T11:31:12.736403827Z"}}