CVE-2026-42505

Description

Handshakes which used Encrypted Client Hello could be de-anonymized by a passive network observer due to a disclosure of pre-shared key identities in the unencrypted client hello.

CVSS Metrics

• v3.1•MEDIUM•Score: 5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Techniques & Countermeasures

• CWE-201•Insertion of Sensitive Information Into Sent Data

  The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor.

Affected Systems

• go standard library•crypto/tls

  < 1.25.12 | ≥ 1.26.0-0, < 1.26.5 | ≥ 1.27.0-0, < 1.27.0-rc.2

• Go•stdlib

  ≥ 1.27.0-0, < 1.27.0-rc.2

References (4)

• https://go.dev/cl/775960
• https://go.dev/issue/79282
• https://groups.google.com/g/golang-announce/c/OrmQE_Yp5Sc
• https://pkg.go.dev/vuln/GO-2026-5856