CVE-2026-42505

Invoking Encrypted Client Hello privacy leak in crypto/tls

State: Published
Severity: 5.3 Medium
Published: Jul 8, 2026
Updated: Jul 8, 2026
Reserved: Apr 28, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	5.3 Medium	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N	CISA-ADP

Weaknesses

CWE-201 Insertion of Sensitive Information Into Sent Data

Affected Products

Product	Versions
crypto/tlsGo standard library	before 1.25.12Affected 1.26.0-0 to before 1.26.5Affected 1.27.0-0 to before 1.27.0-rc.2Affected

References

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

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