Vulnerability in Go Standard Library Mime

CVE-2026-42504

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

Published · last modified .

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.

EPSS exploit prediction

EPSS: 0.006 (44.4th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 44th percentile — 44.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-42504: held from 0.006 to 0.006.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

Weakness classification (CWE)

References

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.