Linux Kernel up to 5.9.1 events_base.c use after free

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
4.9	$0-$5k	0.00

A vulnerability, which was classified as problematic, was found in Linux Kernel up to 5.9.1 (Operating System). Affected is an unknown function of the file drivers/xen/events/events_base.c. The manipulation with an unknown input leads to a memory corruption vulnerability. CWE is classifying the issue as CWE-416. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

An issue was discovered in the Linux kernel through 5.9.1, as used with Xen through 4.14.x. drivers/xen/events/events_base.c allows event-channel removal during the event-handling loop (a race condition). This can cause a use-after-free or NULL pointer dereference, as demonstrated by a dom0 crash via events for an in-reconfiguration paravirtualized device, aka CID-073d0552ead5.

The weakness was released 10/23/2020. The advisory is available at git.kernel.org. This vulnerability is traded as CVE-2020-27675 since 10/22/2020. The attack needs to approached within the local network. The successful exploitation requires a authentication. Technical details are known, but there is no available exploit. The structure of the vulnerability defines a possible price range of USD $0-$5k at the moment (estimation calculated on 11/26/2020).

Applying a patch is able to eliminate this problem.

Productinfoedit

Type

Operating System

Vendor

Linux

Name

Kernel

CPE 2.3infoedit

CPE 2.2infoedit

CVSSv3infoedit

VulDB Meta Base Score: 5.1
VulDB Meta Temp Score: 4.9

VulDB Base Score: 5.5
VulDB Temp Score: 5.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 4.7
NVD Vector: 🔒

CVSSv2infoedit

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

NVD Base Score: 🔒

Exploitinginfoedit

Class: Memory corruption
CWE: CWE-416
ATT&CK: Unknown

Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfoedit

Threat: 🔍
Adversaries: 🔍
Geopolitics: 🔍
Economy: 🔍
Predictions: 🔍
Remediation: 🔍

Countermeasuresinfoedit

Recommended: Patch
Status: 🔍

0-Day Time: 🔒

Timelineinfoedit

10/22/2020 CVE assigned
10/23/2020 +1 days Advisory disclosed
10/23/2020 +0 days VulDB entry created
11/26/2020 +34 days VulDB last update

Sourcesinfoedit

Vendor: https://www.kernel.org/

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2020-27675 (🔒)

Entryinfoedit