CVE-2026-42245: Ruby-Lang Net::imap

High severity, CVSS 7.5. EPSS: 0.7% chance of exploitation in the next 30 days.

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.4.24, 0.5.14, and 0.6.4, Net::IMAP::ResponseReader has quadratic time complexity when reading large responses containing many string literals. A hostile server can send responses which are crafted to exhaust the client's CPU for a denial of service attack. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.

Affected products

• Ruby-Lang Net::imap: before 0.4.24 (fixed in 0.4.24); from 0.5.0, before 0.5.14 (fixed in 0.5.14); from 0.6.0, before 0.6.4 (fixed in 0.6.4)

Published 2026-05-09. Last modified 2026-07-24.