CVE-2026-44726
Deno: TLS retry copies stale upgrade hook, risking plaintext traffic
Description
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.
CVSS Vector Breakdown
AV:NAttack VectorAC:HAttack ComplexityPR:NPrivileges RequiredUI:NUser InteractionS:UScopeC:HConfidentialityI:HIntegrityA:NAvailabilityWeaknesses
Affected Products
Exploitability
Attack Graph
Click technique nodes for MITRE ATT&CK details · drag to pan · Ctrl/⌘ + scroll to zoom, or go fullscreen.
MITRE ATT&CK
2 techniquesReferences
Unlock Complete Vulnerability Intelligence
Get the full picture for CVE-2026-44726 and every CVE in our database. Create a free account — no credit card required.
Create Free Account