CVE-2026-42504
HighCVSS 7.5Exploitation Probability (EPSS)
Low risk43th percentile - higher than 43% of all known CVEs
Summary
Decoding a maliciously-crafted MIME header containing many invalid encoded-words can consume excessive CPU resources.
Risk Assessment
The risk is a denial of service attack via specially crafted email or other MIME resource, potentially slowing or crashing the system.
Recommendation
Apply patches from the MIME-handling software vendor and implement limits on header processing.
Other vulnerabilities in MIME parser
See all- CVE-2026-116273Low risk· EPSS 7%
MIME::Parser versions before 5.521 for Perl set no limit on the number of message parts by default, allowing memory exhaustion. The max_parts option defaulted to -1 (no limit); version 5.521 sets max_parts to 1000 and max_depth to 64 by default.
- CVE-2026-116267Low risk· EPSS 7%
MIME::Parser versions before 5.521 for Perl allow memory exhaustion via indented error messages from a truncated, deeply nested message. Each stored parser diagnostic is indented by three spaces per nesting level, and when a message nested N levels deep ends without its closing boundaries, every level logs an error at its own depth, so the stored diagnostics grow with the square of N. The defaults place no limit on nesting depth.
Original NVD description (English source)
Decoding a maliciously-crafted MIME header containing many invalid encoded-words can consume excessive CPU.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS