I'm not really sure if this is a bug of missingsummary or Extension:ConfirmEdit, but together they produce an infinite loop of Captcha-solving and missingsummary-warnings.

Steps to reproduce:

1. As an anonymous user, edit a page, add an external Link and click save
2. You will have to solve a Captcha.
3. You will get a warning about your missing summary.
4. Continue at 2.

Version: unspecified
Severity: normal