net-imap vulnerable to command Injection via unvalidated Symbol inputs — CVE-2026-42258

Summary

### Summary Symbol arguments to commands are vulnerable to a CRLF Injection / IMAP Command injection via Symbol arguments passed to IMAP commands. ### Details Symbol arguments represent IMAP "system flags", which are formatted as "atoms" (with no quoting) with a `"\"` prefix. Vulnerable versions of Net::IMAP sends the symbol name directly to the socket, with no validation. Because the Symbol input is unvalidated,…

Product

rubygems: net-imap

What to do

General, cautious steps (verify details in the official source):

• Review exposure and plan remediation based on risk and environment.
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

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