CVE-2026-47240

A flaw was found in Net::IMAP, a Ruby library that provides Internet Message Access Protocol (IMAP) client functionality. This vulnerability allows a remote attacker to inject arbitrary IMAP commands. This is possible when an IMAP server does not support non-synchronizing literals, leading to the misinterpretation of data as new commands. This command injection could enable unauthorized actions on the IMAP server.

This Moderate flaw in the Net::IMAP Ruby library allows for command injection against IMAP servers that lack support for non-synchronizing literals. An attacker could exploit this by providing specially crafted input, leading to the execution of arbitrary IMAP commands and potential unauthorized actions. This risk is primarily present in deployments interacting with older or non-standard IMAP server configurations.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Explicitly validate user-controlled inputs to prevent embedded non-synchronizing literals unless the server supports them. For a simpler, more cautious approach: all embedded literals can be unconditionally prohibited, by checking that string inputs do not contain any CR or LF bytes.