CVE-2026-47242: Ruby Net::IMAP command injection in ID and ENABLE commands

CVE-2026-47242 · Severity: medium · CVSS 4 · Published 2026-06-22

Net::IMAP is a Ruby library used by applications to communicate with email servers. A security flaw allows an attacker to inject unauthorized commands into the email session if the application uses untrusted data for certain settings. This could allow an attacker to perform unauthorized actions on a mailbox, such as deleting messages, though it is only exploitable if the application is specifically designed to pass user-controlled input into these internal functions.

Technologies: net-imap (RubyGems). Vendors: RubyGems.

Quick answers

Is CVE-2026-47242 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-47242 being exploited in the wild.
How severe is CVE-2026-47242?
Medium severity, with a CVSS score of 4, published 22 June 2026.
Which products and versions are affected?
net-imap (RubyGems) ECOSYSTEM:introduced=0.6.0,fixed=0.6.4.1.
Is there a fix for CVE-2026-47242?
Yes. net-imap (RubyGems): upgrade to 0.6.4.1 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-47242 attacked?
It is attacked with local access, in a software library.
Am I affected by CVE-2026-47242?
Check whether you run net-imap (RubyGems) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • net-imap (RubyGems): upgrade to 0.6.4.1 or later
    bundle update net-imap

Technical details

A command injection vulnerability exists in the Ruby Net::IMAP library due to improper neutralization of CRLF sequences in the #id and #enable methods. When #id is called with a hash argument, the library fails to validate field values against newline characters, even though it correctly escapes other special characters. Similarly, the #enable method does not validate its arguments as valid IMAP atoms, sending the string representation verbatim to the server. An attacker who can influence these arguments can inject a CRLF sequence followed by arbitrary IMAP commands (e.g., DELETE). Exploitation typically requires the application to pass untrusted user input into these specific client configuration methods. The issue is resolved in versions 0.6.4.1 and 0.5.15.

Affected products

  • Ruby net-imap >= 0.6.0, < 0.6.4.1; < 0.5.15

Identifiers

  • CVE-2026-47242
  • GHSA-46q3-7gv7-qmgg

Timeline

  • 2026-06-09: advisory: GitHub Security Advisory published
  • 2026-06-22: disclosed: CVE published to NVD

References

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