What is CVE-2026-42504?

CVE-2026-42504 is a high-severity vulnerability in Go Standard Library Mime, classified under Inefficient Algorithmic Complexity. CVSS score: 7.5/10. Published 2026-06-02.

How severe is CVE-2026-42504?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Go Standard Library Mime

CVE-2026-42504

Decoding a maliciously-crafted MIME header containing many invalid encoded-words can consume excessive CPU.

EPSS: 0.000 (12.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Go Standard Library Mime — versions 0, 1.26.0-0

Weakness classification (CWE)

CWE-407 — Inefficient Algorithmic Complexity

References

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

Frequently asked questions

What is CVE-2026-42504?: CVE-2026-42504 is a high-severity vulnerability in Go Standard Library Mime, classified under Inefficient Algorithmic Complexity. CVSS score: 7.5/10. Published 2026-06-02.
How severe is CVE-2026-42504?: High severity. CVSS v3 base score is 7.5 out of 10.