CVE-2026-42505

MEDIUM 5.3

Invoking Encrypted Client Hello privacy leak in crypto/tls

CVSS Score

5.3

EPSS Score

0.0%

EPSS Percentile

0th

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.

Vendor	go standard library
Product	crypto/tls
Published	Jul 8, 2026
Last Updated	Jul 8, 2026

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Affected Versions

Go standard library / crypto/tls

0 < 1.25.12 1.26.0-0 < 1.26.5 1.27.0-0 < 1.27.0-rc.2

References

NVD ↗ CVE.org ↗ EPSS Data ↗

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

Credits

Coia Prant (github.com/rbqvq)