CGI has Denial of Service (DoS) potential in Cookie.parse

There is a possibility for DoS by in the cgi gem.
This vulnerability has been assigned the CVE identifier CVE-2025-27219. We recommend upgrading the cgi gem.

Details

CGI::Cookie.parse took super-linear time to parse a cookie string in some cases. Feeding a maliciously crafted cookie string into the method could lead to a Denial of Service.

Please update CGI gem to version 0.3.5.1, 0.3.7, 0.4.2 or later.

Affected versions

cgi gem versions <= 0.3.5, 0.3.6, 0.4.0 and 0.4.1.

Credits

Thanks to lio346 for discovering this issue.
Also thanks to mame for fixing this vulnerability.