Charlie Somerville discovered that Ruby incorrectly handled floating point number conversion. If an application using Ruby accepted untrusted input strings and converted them to floating point numbers, an attacker able to provide such input could cause the application to crash or, possibly, execute arbitrary code with the privileges of the application.
For the oldstable distribution (squeeze), this problem has been fixed in version 220.127.116.11-2+deb6u2.
For the stable distribution (wheezy), this problem has been fixed in version 18.104.22.168-8.1+deb7u2.
For the unstable distribution (sid), this problem has been fixed in version 22.214.171.1244-1.
We recommend that you upgrade your ruby1.9.1 packages.