GHSA-8p34-64r3-mwg8: Net::IMAP: Command Injection via non-synchronizing literal in "raw" argument

Several Net::IMAP commands accept a "raw data" argument that is sent verbatim after validation to prevent command injection. However, if a server does not support non-synchronizing literals, it may still be possible to inject arbitrary IMAP commands inside non-synchronizing literals. Details Raw data arguments support embedded literal values, both synchronizing and non-synchronizing. Non-synchronizing literals can only be safely sent when the server advertises any of the LITERAL+, LITERAL-, or IMAP4rev2 capabilities. But raw data arguments do not verify server support for non-synchronizing literals prior to sending. Servers without support for non-synchronizing literals could handle them in several different ways: If a server sees a "}\r\n" byte sequence but can't parse the literal bytesize, it _may_ cautiously decide to close the connection, blocking any command injection attacks. However, a server without support for non-synchronizing literals may instead interpret the "+}\r\n" as the end of a malformed command line and respond with a tagged BAD. In that case, the contents of the literal will be interpreted as one or more new pipelined commands, allowing a CRLF command injection attack to succeed. This affects the following commands' string arguments: - criteria for #search and #uid_search - search_keys for #sort, #thread, #uid_sort, and #uid_thread - attr for #fetch and #uid_fetch Prior to net-imap v0.6.4, v0.5.14, and v0.4.24, raw data arguments were not validated in _any_ way, so they were also vulnerable to this attack. See CVE-2026-42257 (GHSA-hm49-wcqc-g2xg). Impact Fortunately, LITERAL- is supported by most modern IMAP servers. Even without support for non-synchronizing literals, cautious servers may handle invalid literal bytesize by closing the connection . However, servers which handle a non-synchronizing literal just like any other malformed command will enable this vulnerability. If a developer passes an unvalidated user-controlled input for on