CVE-2026-47241 Net::IMAP: Denial of Service via incomplete raw argument validation
Attackers can cause a denial of service in Ruby's Net::IMAP library by sending crafted raw arguments that block command execution.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-47241?
CVE-2026-47241 is a low-severity denial of service vulnerability in ruby net-imap, published on 22 Jun 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to 0.6.5 and 0.5.15, several Net::IMAP commands accept a raw string argument which is only validated to prevent CRLF injection and then sent verbatim. If this string is derived from user-controlled input, an attacker can force the next command to be absorbed as a continuation of the first command. This will cause the first command to eventually fail, but also prevents it from returning until another command is sent (from another thread). That other command will not return until the connection is closed. This vulnerability is fixed in 0.6.5 and 0.5.15.
Which versions are affected by CVE-2026-47241?
4 open source packages ship an affected version, including net-imap.
| Package | Affected | Fixed in |
|---|---|---|
net-imap RubyGems | All versions | 0.5.15 |
net-imap RubyGems | All versions | 0.5.15 |
net-imap RubyGems | From 0.6.0 | 0.6.4.1 |
net-imap RubyGems | From 0.6.0 | 0.6.4.1 |
How do I fix CVE-2026-47241?
Upgrade net-imap to a fixed version for your release line: 0.5.15 or 0.6.4.1.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-47241 being exploited?
There is no known exploitation of CVE-2026-47241 in the wild and no public exploit code.
Sources
Also known as ALPINE-CVE-2026-47241, BELL-CVE-2026-47241, CLEANSTART-2026-HQ73324, CLEANSTART-2026-NQ87624, DEBIAN-CVE-2026-47241, ECHO-bf99-96ee-af6b and 17 more.