CVE-2026-44726 Details
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.
A vulnerability exists in Deno versions 2.0.0 through 2.7.8 within the Node.js TLS compatibility layer. This flaw can lead to a TLS client sending application data unencrypted after a connection retry. When 'autoSelectFamily' was enabled and the initial address-family attempt failed, the socket reinitialization process reused an outdated TLS upgrade hook linked to the original, unsuccessful handle. Consequently, the new TCP connection did not upgrade to TLS, allowing any data written by the application before the 'secureConnect' event to be transmitted over the network in plaintext. A network attacker could exploit this by causing the first connection attempt to fail, such as by disrupting IPv6 traffic on a dual-stack host, and then intercept or modify the unencrypted data that the application believed was protected by TLS.
Users can upgrade to Deno version 2.7.8 or later to address this vulnerability.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Jun 25, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/denoland/deno/security/advisories/GHSA-chqv-56wv-7564 | [email protected] | ExploitVendor Advisory |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-319 | Cleartext Transmission of Sensitive Information | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| deno deno | >= 2.0.0, < 2.7.8 |
CPE
Remediation
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Change History
5 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jun 26, 2026 | Initial Analysis | [email protected] |
| Jun 25, 2026 | CVE Modified | CISA-ADP |
| Jun 25, 2026 | CVE Modified | CISA-ADP |
| Jun 24, 2026 | CVE Modified | CISA-ADP |
| Jun 23, 2026 | New CVE Received | [email protected] |