Sensitive information disclosure

Oct 13, 2025 by pynkocean.com 58 views

CVE-2019-9636: A Critical Vulnerability in Python 2.7 and 3.x

Overview

Description

The vulnerability occurs when the urllib.parse.urlsplit or urllib.parse.urlparse function is used to parse a URL with an incorrect netloc (network location). This can lead to information disclosure, as the function may cache credentials, cookies, or other sensitive information against a given hostname. An attacker can exploit this vulnerability by crafting a specially designed URL that is incorrectly parsed, allowing them to access sensitive information.

Impact

The impact of this vulnerability is significant, as it allows an attacker to perform information disclosure. This can lead to a range of consequences, including:

Credentials theft: An attacker can steal sensitive credentials, such as usernames and passwords, by accessing the cached information.
Cookie theft: An attacker can steal cookies, which can be used to access sensitive information or perform malicious actions.
Sensitive information disclosure: An attacker can access sensitive information, such as API keys or other confidential data.

Components Affected

The following components are affected by this vulnerability:

urllib.parse.urlsplit
urllib.parse.urlparse

Attack Vector

The attack vector for this vulnerability is a specially crafted URL that is incorrectly parsed. This can be achieved by an attacker by:

Crafting a malicious URL: An attacker can craft a malicious URL that is designed to be incorrectly parsed by the urllib.parse.urlsplit or urllib.parse.urlparse function.
Exploiting a vulnerable application: An attacker can exploit a vulnerable application that uses the urllib.parse.urlsplit or urllib.parse.urlparse function to parse URLs.

Fixed Versions

The following versions of Python are fixed:

Python 2.7: Version 2.7.17 and later
Python 3.x: Version 3.5.10 and later, version 3.6.10 and later, and version 3.7.3 and later

Remediation

To remediate this vulnerability, you should:

Upgrade to a fixed version: Upgrade to a fixed version of Python, such as version 2.7.17 or later, or version 3.5.10 or later.
Use a secure URL parsing library: Use a secure URL parsing library, such as urllib.parse.urlsplit or urllib.parse.urlparse, to parse URLs.

References

The following references provide additional information on this vulnerability:

NVD Description: https://nvd.nist.gov/vuln/detail/CVE-2019-9636
Remediation: https://www.python.org/downloads/
Fixed Versions: https://www.python.org/downloads/
References: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-9636

Additional Information

The following additional information is available:

Debian Security Advisory: https://security-tracker.debian.org/tracker/CVE-2019-9636
Fedora Security Advisory: https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2ORNTF62QPLMJXIQ7KTZQ2776LMIXEKL/
Gentoo Security Advisory: https://security.gentoo.org/glsa/202003-26
Ubuntu Security Notice: https://usn.ubuntu.com/4127-1/

Conclusion

CVE-2019-9636 is a critical vulnerability in Python 2.7 and 3.x that affects the urllib.parse.urlsplit and urllib.parse.urlparse functions. This vulnerability allows an attacker to perform information disclosure by incorrectly parsing URLs and sending sensitive information to a different host. To remediate this vulnerability, you should upgrade to a fixed version of Python or use a secure URL parsing library.
CVE-2019-9636: A Critical Vulnerability in Python 2.7 and 3.x - Q&A

Q: What is CVE-2019-9636?

A: CVE-2019-9636 is a critical vulnerability in Python 2.7 and 3.x that affects the urllib.parse.urlsplit and urllib.parse.urlparse functions. This vulnerability allows an attacker to perform information disclosure by incorrectly parsing URLs and sending sensitive information to a different host.

Q: What is the impact of this vulnerability?

A: The impact of this vulnerability is significant, as it allows an attacker to perform information disclosure. This can lead to a range of consequences, including:

Credentials theft: An attacker can steal sensitive credentials, such as usernames and passwords, by accessing the cached information.
Cookie theft: An attacker can steal cookies, which can be used to access sensitive information or perform malicious actions.
Sensitive information disclosure: An attacker can access sensitive information, such as API keys or other confidential data.

Q: Which components are affected by this vulnerability?

A: The following components are affected by this vulnerability:

urllib.parse.urlsplit
urllib.parse.urlparse

Q: What is the attack vector for this vulnerability?

A: The attack vector for this vulnerability is a specially crafted URL that is incorrectly parsed. This can be achieved by an attacker by:

Crafting a malicious URL: An attacker can craft a malicious URL that is designed to be incorrectly parsed by the urllib.parse.urlsplit or urllib.parse.urlparse function.
Exploiting a vulnerable application: An attacker can exploit a vulnerable application that uses the urllib.parse.urlsplit or urllib.parse.urlparse function to parse URLs.

Q: How can I remediate this vulnerability?

A: To remediate this vulnerability, you should:

Upgrade to a fixed version: Upgrade to a fixed version of Python, such as version 2.7.17 or later, or version 3.5.10 or later.
Use a secure URL parsing library: Use a secure URL parsing library, such as urllib.parse.urlsplit or urllib.parse.urlparse, to parse URLs.

Q: What are the fixed versions of Python that address this vulnerability?

A: The following versions of Python are fixed:

Python 2.7: Version 2.7.17 and later
Python 3.x: Version 3.5.10 and later, version 3.6.10 and later, and version 3.7.3 and later

Q: Are there any additional resources available for this vulnerability?

A: Yes, the following additional resources are available:

NVD Description: https://nvd.nist.gov/vuln/detail/CVE-2019-9636
Remediation: https://www.python.org/downloads/
Fixed Versions: https://www.python.org/downloads/
References: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-9636

Q: Is this vulnerability specific to Python?

A: No, this vulnerability is not specific to Python. However, the urllib.parse.urlsplit and urllib.parse.urlparse functions are part of the Python standard library, and this vulnerability affects these functions.

Q: Can I use a workaround to mitigate this vulnerability?

A: Yes, you can use a workaround to mitigate this vulnerability. However, it is recommended to upgrade to a fixed version of Python or use a secure URL parsing library to ensure that your application is secure.

Q: How can I stay informed about security vulnerabilities in Python?

A: You can stay informed about security vulnerabilities in Python by:

Subscribing to the Python Security mailing list: https://mail.python.org/mailman/listinfo/python-security
Following the Python Security blog: https://python-security.readthedocs.io/
Checking the Python Security Advisory page: https://www.python.org/downloads/security/