oss-sec mailing list archives

big ints in python: CVE-2020-10735


From: Georgi Guninski <gguninski () gmail com>
Date: Wed, 21 Sep 2022 09:17:21 +0300

There was recent discussion of big ints in python and libgmp.

https://docs.python.org/3.10/whatsnew/changelog.html#security

===
gh-95778: Converting between int and str in bases other than 2
(binary), 4, 8 (octal), 16 (hexadecimal), or 32 such as base 10
(decimal) now raises a ValueError if the number of digits in string
form is above a limit to avoid potential denial of service attacks due
to the algorithmic complexity. This is a mitigation for CVE-2020-10735
====

https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-10735
===
In algorithms with quadratic time complexity using non-binary bases ...
The highest threat from this vulnerability is to system availability.
===

AFAICT the quadratic complexity is quadratic in the size of the int,
that is its logarithm.


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