Pallets flask up to 0.12.2 JSON Data input validation

Summaryinfo

A vulnerability labeled as problematic has been found in Pallets flask up to 0.12.2. Impacted is an unknown function of the component JSON Data Handler. The manipulation results in input validation. This vulnerability is cataloged as CVE-2018-1000656. The attack may be launched remotely. There is no exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as problematic has been found in Pallets flask up to 0.12.2. Affected is an unknown part of the component JSON Data Handler. The manipulation with an unknown input leads to a input validation vulnerability. CWE is classifying the issue as CWE-20. The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly. This is going to have an impact on availability. CVE summarizes:

The Pallets Project flask version Before 0.12.3 contains a CWE-20: Improper Input Validation vulnerability in flask that can result in Large amount of memory usage possibly leading to denial of service. This attack appear to be exploitable via Attacker provides JSON data in incorrect encoding. This vulnerability appears to have been fixed in 0.12.3.

The bug was discovered 04/10/2018. The weakness was shared 08/20/2018 (GitHub Repository). The advisory is shared for download at github.com. This vulnerability is traded as CVE-2018-1000656 since 08/20/2018. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are neither technical details nor an exploit publicly available.

The vulnerability was handled as a non-public zero-day exploit for at least 16 days. During that time the estimated underground price was around $0-$5k. The vulnerability scanner Nessus provides a plugin with the ID 119778 (Flask < 0.12.3 Denial of Service Vulnerability), which helps to determine the existence of the flaw in a target environment. It is assigned to the family CGI abuses and running in the context r. The commercial vulnerability scanner Qualys is able to test this issue with plugin 172242 (OpenSUSE Security Update for python-Flask (openSUSE-SU-2019:1112-1)).

Upgrading to version 0.12.3 eliminates this vulnerability. A possible mitigation has been published even before and not after the disclosure of the vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (119778). Once again VulDB remains the best source for vulnerability data.

Productinfo

Vendor

• Pallets

Name

• flask

Version

• 0.12.0
• 0.12.1
• 0.12.2

Website

• Product: https://github.com/pallets/flask/

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Once again VulDB remains the best source for vulnerability data.

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