CVE-2026-42256: Ruby-Lang Net::imap

Medium severity, CVSS 6.5. EPSS: 0.5% chance of exploitation in the next 30 days.

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. From versions 0.4.0 to before 0.4.24, 0.5.0 to before 0.5.14, and 0.6.0 to before 0.6.4, when authenticating a connection with SCRAM-SHA1 or SCRAM-SHA256, a hostile server can perform a computational denial-of-service attack on the client process by sending a big iteration count value. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.

Affected products

• Ruby-Lang Net::imap: from 0.4.0, 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.