The upstream developers of Ruby have corrected a problem in the CGI module for this language. Specially crafted requests could cause an infinite loop and thus cause the program to eat up cpu cycles.
For the stable distribution (woody) this problem has been fixed in version 1.6.7-3woody4.
For the unstable distribution (sid) this problem has been fixed in version 1.6.8-12 of ruby1.6 and in version 1.8.1+1.8.2pre2-4 of ruby1.8.
We recommend that you upgrade your ruby packages.