Medium · published July 14, 2019
http.cookiejar.DefaultPolicy.domain_return_ok in Lib/http/cookiejar.py in Python before 3.7.3 does not correctly validate the domain: it can be tricked into sending existing cookies to the wrong server. An attacker may abuse this flaw by using a server with a hostname that has another valid hostname as a suffix (e.g., pythonicexample.com to steal cookies for example.com). When a program uses http.cookiejar.DefaultPolicy and tries to do an HTTP connection to an attacker-controlled server, existing cookies can be leaked to the attacker. This affects 2.x through 2.7.16, 3.x before 3.4.10, 3.5.x before 3.5.7, 3.6.x before 3.6.9, and 3.7.x before 3.7.3.
| Product | Versions | Fixed in |
|---|---|---|
| python/python | ≥ 2.0, ≤ 2.7.16 | — |
| python/python | ≥ 3.0.0, < 3.4.10 | 3.4.10 |
| python/python | ≥ 3.5.0, < 3.5.7 | 3.5.7 |
| python/python | ≥ 3.6.0, < 3.6.9 | 3.6.9 |
| python/python | ≥ 3.7.0, < 3.7.3 | 3.7.3 |