Coordinated Disclosure Timeline
- 2021-08-31: Sent report to lead2gold@gmail.com (@caronc)
- 2021-08-31: Reply from lead2gold@gmail.com: “I’ll look into this as soon as I can.”
- 2021-09-06: Issue is fixed.
Summary
Apprise contains a regular expression that is vulnerable to ReDoS (Regular Expression Denial of Service).
Product
Apprise
Tested Version
Details
ReDoS
ReDoS, or Regular Expression Denial of Service, is a vulnerability affecting inefficient regular expressions which can perform extremely badly when run on a crafted input string.
This vulnerability was found using a CodeQL query which identifies inefficient regular expressions. You can see the results of the query on Apprise by following this link.
Vulnerability
The vulnerable regular expression is here.
To see that the regular expression is vulnerable, copy-paste it into a separate file as shown below:
- Run the code below with
python3:
import re
m = re.match(
r'^https?://maker\.ifttt\.com/use/'
r'(?P<webhook_id>[A-Z0-9_-]+)'
r'/?(?P<events>([A-Z0-9_-]+/?)+)?'
r'/?(?P<params>\?.+)?$', "http://maker.ifttt.com/use/------------------------------------------------------------|", re.I)
Impact
This issue may lead to a denial of service.
Credit
This issue was discovered by GitHub team members @erik-krogh (Erik Krogh Kristensen) and @yoff (Rasmus Petersen).
Contact
You can contact the GHSL team at securitylab@github.com, please include a reference to GHSL-2021-120 in any communication regarding this issue.