What is CVE-2026-39821?

CVE-2026-39821 is a security advisory published by Microsoft Security Response Center (MSRC) with Critical severity. Invoking failure to reject ASCII-only Punycode-encoded labels in golang.org/x/net/idna

Which CVE IDs does CVE-2026-39821 cover?

CVE-2026-39821 covers the following CVE IDs: CVE-2026-39821. Each CVE has its own detail page on EchelonGraph Pulse with the synthesized EG score.

What is the CVSS v3 score of CVE-2026-39821?

CVE-2026-39821 has a CVSS v3 base score of 10.0, published by Microsoft Security Response Center (MSRC).

CVE-2026-39821CriticalCVSS 10.0

Invoking failure to reject ASCII-only Punycode-encoded labels in golang.org/x/net/idna

Vendor

Microsoft Security Response Center (MSRC)

Published

May 28, 2026

Last Modified

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🔗 CVE IDs covered (1)

CVE-2026-39821 →