CVE-2026-42257
Critical
Description
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, several Net::IMAP commands accept a raw string argument that is sent to the server without validation or escaping. If this string is derived from user-controlled input, it may contain contain CRLF sequences, which an attacker can use to inject arbitrary IMAP commands. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.
SeverityCritical
CVSS9.8
Exploit probability—
ProductRuby-lang Net\
PublishedMay 9, 2026
First seenMay 9, 2026
Weakness typeCWE-93CWE-93CWE-77Command injection
How to fix
Update
- ruby-lang net\0.4.24, 0.5.14, 0.6.4 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| ruby-lang net\ | \ ≤ v < 0.4.24, 0.5.0 ≤ v < 0.5.14, 0.6.0 ≤ v < 0.6.4 | 0.4.24, 0.5.14, 0.6.4 |
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