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.
Fix
Patch, vendor advisory and mitigation references on NVD 1
- https://github.com/denoland/deno/security/advisories/GHSA-chqv-56wv-7564 Exploit, Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 9.1 · denoNVD modified 2026-10-25 23:10
Affected (CPE criteria) 1
cpe:2.3:a:deno:deno:*:*:*:*:*:*:*:*
References 1
- https://github.com/denoland/deno/security/advisories/GHSA-chqv-56wv-7564 Exploit, Vendor Advisory