H2O versions 2.0.3 and earlier and 2.1.0-beta2 and earlier allows remote attackers to cause a denial-of-service (DoS) via format string specifiers in a template file via fastcgi, mruby, proxy, redirect or reproxy.
The product uses a function that accepts a format string as an argument, but the format string originates from an external source.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| H2o | Dena | 2.0.0 (including) | 2.0.3 (including) |
| H2o | Dena | 2.1.0 (including) | 2.1.0 (including) |
| H2o | Dena | 2.1.0-beta1 (including) | 2.1.0-beta1 (including) |