SMTP Command Injection Vulnerability in Ruby Mail Package
Summary
DEBIAN-CVE-2015-9097: The mail gem before 2.5.5 for Ruby (aka A Really Ruby Mail Library) is vulnerable to SMTP command injection via CRLF sequences in a RCPT TO or MAIL FROM command, as demonstrated by CRLF sequences immediately before and a... Affects ruby-mail versions < 2.6.1+dfsg1-1. Fixed in 2.6.1+dfsg1-1. How to fix ↓
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Background
The Ruby Mail package is a widely used library in Ruby applications that facilitates the sending and receiving of emails. It provides a simple interface for constructing and sending email messages, handling attachments, and managing email protocols. However, prior to version 2.5.5, the Ruby Mail package is susceptible to a critical vulnerability that allows attackers to exploit SMTP commands, potentially compromising the integrity of email communications.
Vulnerability Detail
The vulnerability arises from improper handling of CRLF (Carriage Return Line Feed) sequences in SMTP commands, specifically within the RCPT TO or MAIL FROM commands. This flaw enables attackers to inject arbitrary SMTP commands, leading to unauthorized actions such as email spoofing or message manipulation. The vulnerability was identified in versions of the Ruby Mail package before 2.5.5, and it poses significant risks to applications relying on this library for email functionalities.
How To Fix
Minimum fixed version
2.6.1+dfsg1-1
This is the first release that contains the fix.
sudo apt-get install --only-upgrade ruby-mailTip — Not sure which version your app runs? Vulert can match this fix to it. Scan free →
Workaround
As a temporary measure, you can sanitize input to the RCPT TO and MAIL FROM commands by stripping out any CRLF sequences before processing. This can be done using the following Ruby code snippet:
def sanitize_smtp_command(command)
command.gsub(/\r\n/, '')
end
This function will help mitigate the risk until the package is updated.
Conclusion
The Ruby Mail package has a critical vulnerability that allows SMTP command injection through improper handling of CRLF sequences. It is crucial to update to the patched version to safeguard your applications from potential exploits. Additionally, implementing input sanitization can provide a temporary solution until the update is applied.
See every vulnerability recorded for ruby-mail →
FAQ
Ruby Mail is a library that allows Ruby applications to send and receive emails easily, providing functionalities for constructing messages and managing email protocols.
The vulnerability allows attackers to inject arbitrary SMTP commands through CRLF sequences, potentially leading to email spoofing and manipulation.
You can use the Vulert platform to monitor and alert for open-source vulnerabilities in your software. Visit Vulert Scanner to check if your application is affected without needing to sign up.
Failing to address this vulnerability can lead to unauthorized email actions, data breaches, and damage to your application's reputation.
Yes, you can sanitize SMTP commands by removing CRLF sequences from user inputs as a temporary workaround until the package is updated.
References
Related vulnerabilities
Recent vulnerabilities recorded for ruby-mail.
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