CVE-2026-47241

Name of the Vulnerable Software and Affected Versions Net::IMAP versions prior to 0.5.15 Net::IMAP versions prior to 0.6.5

Description Several commands in the Net::IMAP Ruby client accept raw string arguments that are only validated to prevent CRLF injection and are then sent verbatim. An incorrect regular expression in the trailing-marker check fails to match {0} or {0+}, allowing attacker-controlled strings ending in these markers to pass validation. When these arguments are sent, the server interprets the trailing CRLF as part of a literal prefix, causing the next command sent by the client to be absorbed as a continuation of the first. This results in the first command eventually failing and the second command hanging until the connection is closed, potentially leading to a denial of service through unexpected crashes and timeouts. This issue is particularly impactful in multi-threaded environments.

The affected components include:

Recommendations Update to version 0.5.15 or 0.6.5. As a temporary workaround, validate that user input provided to the affected command arguments does not end with the } character. Implement Timeout or other standard strategies for managing slow connections and misbehaving servers to mitigate the effects of hanging commands.