Regular Expression DoS vulnerabilities in requests_kerberos/kerberos_.py

[yinxiL]

We are working on the ReDoS problem and detected a vulnerable regex from your code.

'(?:.*,)*\s*Negotiate\s*([^,]*),?' in link takes forever to match the string
",,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,\b"

Please try the below:
python3
import re
re.search(r'(?:.*,)*\s*Negotiate\s*([^,]*),?', ",,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,\b");

We suggest you change the structure (?:.*,)*, to (?:.*).

We didn’t create a pull request because we're not sure if these cases are possible to take place in your program, we also do not understand the functionality of these regexes as you do. Thank you for your understanding.