CVE-2026-47242: Ruby Net-Imap

Medium severity, CVSS 5.8. EPSS: 0.2% chance of exploitation in the next 30 days.

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to 0.6.5 and 0.5.15, when Net::IMAP#id is called with a hash argument, although the ID field value strings are correctly quoted (escaping quoted specials), they were not validated to prohibit CRLF sequences. While Net::IMAP#enable does process its arguments for aliases, it does not validate them as valid atoms (or as a list of valid atoms). The #to_s value is sent verbatim. Arguments to either command could be used by an attacker to inject arbitrary IMAP commands. This vulnerability is fixed in 0.6.5 and 0.5.15.

Affected products

• Ruby Net-Imap: from 0.6.0, before 0.6.4.1 (fixed in 0.6.4.1); before 0.5.15 (fixed in 0.5.15)

Published 2026-06-22. Last modified 2026-06-23.