CVE-2026-42504

HIGH
Published Jun 2, 2026 Modified Jun 4, 2026 CWE-407

Description

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

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CVSS v3.1 Score

7.5
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0056
Probability of exploitation
0.42%
Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-407 CWE-407

References

Frequently Asked Questions

What is CVE-2026-42504? +
Decoding a maliciously-crafted MIME header containing many invalid encoded-words can consume excessive CPU. It has a CVSS v3.1 base score of 7.5 (HIGH).
How severe is CVE-2026-42504? +
CVE-2026-42504 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0056, placing it in the 0th percentile for exploitation probability.
How do I check if I'm vulnerable to CVE-2026-42504? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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