Quadratic complexity parsing cookies with backslashes

Vulnerability Description

There is a LOW severity vulnerability affecting CPython, specifically the 'http.cookies' standard library module. When parsing cookies that contained backslashes for quoted characters in the cookie value, the parser would use an algorithm with quadratic complexity, resulting in excess CPU resources being used while parsing the value.

References

• https://github.com/python/cpython/pull/123075
• https://github.com/python/cpython/issues/123067
• https://mail.python.org/archives/list/security-announce@python.org/thread/HXJAAAALNUNGCQUS2W7WR6GFIZIHFOOK/
• https://github.com/python/cpython/commit/391e5626e3ee5af267b97e37abc7475732e67621
• https://github.com/python/cpython/commit/dcc3eaef98cd94d6cb6cb0f44bd1c903d04f33b1
• https://github.com/python/cpython/commit/a77ab24427a18bff817025adb03ca920dc3f1a06
• https://github.com/python/cpython/commit/b2f11ca7667e4d57c71c1c88b255115f16042d9a
• https://github.com/python/cpython/commit/d4ac921a4b081f7f996a5d2b101684b67ba0ed7f
• https://github.com/python/cpython/commit/d662e2db2605515a767f88ad48096b8ac623c774
• https://github.com/python/cpython/commit/44e458357fca05ca0ae2658d62c8c595b048b5ef