PT-2026-56479 · Go Standard Library+1 · Crypto/Tls+1

Coia Prant · Published 2026-07-07 · Updated 2026-07-08 · CVE-2026-42505

Positive Technologies (AI Summary)

CVSS v3.1

5.3

Medium

Base vector

AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Name of the Vulnerable Software and Affected Versions The product name cannot be determined (affected versions not specified)

Description Handshakes using Encrypted Client Hello (ECH), a mechanism designed to encrypt the initial handshake of a TLS connection to protect client privacy, could be de-anonymized by a passive network observer. This occurs because pre-shared key identities are disclosed within the unencrypted portion of the client hello.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.

Weakness Enumeration

CWE-201

Related Identifiers

CVE-2026-42505

GO-2026-5856

Affected Products

Crypto/Tls

Stdlib

References · 6

• https://nvd.nist.gov/vuln/detail/CVE-2026-42505 · Security Note
• https://osv.dev/vulnerability/GO-2026-5856 · Vendor Advisory
• https://go.dev/cl/775960 · Note
• https://go.dev/issue/79282 · Note
• https://pkg.go.dev/vuln/GO-2026-5856 · Note
• https://groups.google.com/g/golang-announce/c/OrmQE_Yp5Sc · Note