Is golang.org/x/net affected by CVE-2026-39821?

Go golang.org/x/net is affected in <0.55.0.

Is CVE-2026-39821 being exploited?

Not on the CISA KEV list. EPSS exploit probability is 0.4%.

medium

CVE-2026-39821

Q: Is CVE-2026-39821 being exploited?

Not on the CISA KEV list. EPSS exploit probability is 0.4%.

Go · golang.org/x/net

Summary

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

Severity: medium
EPSS: 0.4% (p28)
Also known as: GO-2026-5026
Published: 2026-05-22

References

Related advisories

CVE-2026-27136 — medium · Go/golang.org/x/net
CVE-2026-42502 — medium · Go/golang.org/x/net
CVE-2026-25680 — medium · Go/golang.org/x/net
CVE-2026-42506 — medium · Go/golang.org/x/net
CVE-2026-25681 — medium · Go/golang.org/x/net
CVE-2026-33814 — medium · Go/golang.org/x/net
CVE-2026-27141 — medium · Go/golang.org/x/net
CVE-2025-58190 — medium · Go/golang.org/x/net

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Sources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.