Vulnerability identifier: #VU19256

Vulnerability risk: Medium

CVSSv3.1: 4.6 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N/E:U/RL:O/RC:C]

CVE-ID: CVE-2018-20852

CWE-ID: CWE-200

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Python
Universal components / Libraries / Scripting languages

Vendor: Python.org

Description

The vulnerability allows a remote attacker to gain access to potentially sensitive information.

The vulnerability exists due to the "http.cookiejar.DefaultPolicy.domain_return_ok" in the "Lib/http/cookiejar.py" file returns incorrect results during cookie domain checks. A remote attacker can trick a victim to execute a program that uses the "http.cookiejar.DefaultPolicy" to make an HTTP connection to an attacker-controlled server with a hostname that has another valid hostname as a suffix.

Successful exploitation of this vulnerability can allow an attacker to gain unauthorized access to sensitive information on the system, such as existing cookies.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Python: 2.7.0 - 2.7.16, 3.1.0 - 3.1.5, 3.2.0 - 3.2.6, 3.3 - 3.3.6, 3.4.0 - 3.4.9, 3.5.0 - 3.5.6, 3.6.0 - 3.6.8, 3.7.0 - 3.7.2

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External links
http://bugs.python.org/issue35121
http://python-security.readthedocs.io/vuln/cookie-domain-check.html

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.