A denial of service vulnerability in the multipart parsing component of Rack fixed in 2.0.9.2, 2.1.4.2, 2.2.4.1 and 3.0.0.1 could allow an attacker tocraft input that can cause RFC2183 multipart boundary parsing in Rack to take an unexpected amount of time, possibly resulting in a denial of service attack vector. Any applications that parse multipart posts using Rack (virtually all Rails applications) are impacted.
The product uses a regular expression with an inefficient, possibly exponential worst-case computational complexity that consumes excessive CPU cycles.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Rack | Rack_project | * | 2.0.9.2 (excluding) |
| Rack | Rack_project | 2.1.0 (including) | 2.1.4.2 (excluding) |
| Rack | Rack_project | 2.2.0 (including) | 2.2.4.1 (excluding) |
Attackers can create crafted inputs that
intentionally cause the regular expression to use
excessive backtracking in a way that causes the CPU
consumption to spike.