What is CVE-2026-42505?

CVE-2026-42505 is a medium-severity vulnerability in Go Standard Library Crypto/tls, classified under Insertion of Sensitive Information into Sent Data. CVSS score: 5.3/10. Published 2026-07-08.

How severe is CVE-2026-42505?

Medium severity. CVSS v3 base score is 5.3 out of 10.

Vulnerability in Go Standard Library Crypto/tls

CVE-2026-42505

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 v3 metric

CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

Affected products

Go Standard Library Crypto/tls — versions 0, 1.26.0-0, 1.27.0-0

Weakness classification (CWE)

CWE-201 — Insertion of Sensitive Information into Sent Data

References

security@golang.org
security@golang.org
security@golang.org
security@golang.org

Frequently asked questions

What is CVE-2026-42505?: CVE-2026-42505 is a medium-severity vulnerability in Go Standard Library Crypto/tls, classified under Insertion of Sensitive Information into Sent Data. CVSS score: 5.3/10. Published 2026-07-08.
How severe is CVE-2026-42505?: Medium severity. CVSS v3 base score is 5.3 out of 10.