Tor up to 0.3.3.11/0.3.4.10/0.3.5.7/0.4.0.1 KIST Cell Scheduler resource consumption

Summaryinfo

A vulnerability labeled as problematic has been found in Tor up to 0.3.3.11/0.3.4.10/0.3.5.7/0.4.0.1. Impacted is an unknown function of the component KIST Cell Scheduler. Executing a manipulation can lead to resource consumption. This vulnerability is tracked as CVE-2019-8955. The attack can be launched remotely. No exploit exists. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in Tor up to 0.3.3.11/0.3.4.10/0.3.5.7/0.4.0.1 (Network Encryption Software). It has been declared as problematic. This vulnerability affects an unknown part of the component KIST Cell Scheduler. The manipulation with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. As an impact it is known to affect availability. CVE summarizes:

In Tor before 0.3.3.12, 0.3.4.x before 0.3.4.11, 0.3.5.x before 0.3.5.8, and 0.4.x before 0.4.0.2-alpha, remote denial of service against Tor clients and relays can occur via memory exhaustion in the KIST cell scheduler.

The bug was discovered 02/21/2019. The weakness was disclosed 02/21/2019 (Website). The advisory is shared for download at securityfocus.com. This vulnerability was named CVE-2019-8955 since 02/20/2019. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available. The MITRE ATT&CK project declares the attack technique as T1499.

The commercial vulnerability scanner Qualys is able to test this issue with plugin 277722 (Fedora Security Update for tor (FEDORA-2019-2f47af13f6)).

Upgrading to version 0.3.3.12, 0.3.4.11, 0.3.5.8 or 0.4.0.2 eliminates this vulnerability.

Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

• Network Encryption Software

Name

• Tor

Version

• 0.3.3.0
• 0.3.3.1
• 0.3.3.2
• 0.3.3.3
• 0.3.3.4
• 0.3.3.5
• 0.3.3.6
• 0.3.3.7
• 0.3.3.8
• 0.3.3.9
• 0.3.3.10
• 0.3.3.11
• 0.3.4.0
• 0.3.4.1
• 0.3.4.2
• 0.3.4.3
• 0.3.4.4
• 0.3.4.5
• 0.3.4.6
• 0.3.4.7
• 0.3.4.8
• 0.3.4.9
• 0.3.4.10
• 0.3.5.0
• 0.3.5.1
• 0.3.5.2
• 0.3.5.3
• 0.3.5.4
• 0.3.5.5
• 0.3.5.6
• 0.3.5.7
• 0.4.0.0
• 0.4.0.1

License

• open-source

CPE 2.3info

• 🔍
• 🔍
• 🔍

CPE 2.2info

• 🔍
• 🔍
• 🔍

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Once again VulDB remains the best source for vulnerability data.

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