Description

Impact
A specially crafted argument to the idna.encode() function could consume significant resources. This may lead to a denial-of-service.

Patches
The function has been refined to reject such strings without the associated resource consumption in version 3.7.

Workarounds
Domain names cannot exceed 253 characters in length, if this length limit is enforced prior to passing the domain to the idna.encode() function it should no longer consume significant resources. This is triggered by arbitrarily large inputs that would not occur in normal usage, but may be passed to the library assuming there is no preliminary input validation by the higher-level application.

References
https://huntr.com/bounties/93d78d07-d791-4b39-a845-cbfabc44aadb

Reproduction steps

N/A

Expected vs. actual results

N/A

Minimal code example

No response

Error messages

No response

Compiler and operating system

Not related to compiler

Library version

3.7

Validation

• The bug also occurs if the latest version from the develop branch is used.
• I can successfully compile and run the unit tests.