CVE-2020-36557

kernel: race condition between the VT_DISALLOCATE ioctl and closing/opening of ttys, causing a use-after-free in con_shutdown().

Severity Score

5.1

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

A race condition in the Linux kernel before 5.6.2 between the VT_DISALLOCATE ioctl and closing/opening of ttys could lead to a use-after-free.

Una condición de carrera en el kernel de Linux versiones anteriores a 5.6.2 entre el ioctl VT_DISALLOCATE y el cierre/apertura de ttys podría conllevar a un uso de memoria previamente liberada

A use-after-free flaw was found in the Linux kernel’s Virtual Terminal subsystem in how a user calls the VT_DISALLOCATE ioctl during the closing/opening of ttys. This flaw allows a local user to crash the system.

An update that solves 18 vulnerabilities, contains one feature and has 18 fixes is now available. The SUSE Linux Enterprise 15 SP3 kernel was updated to receive various security and bug fixes.

*Credits: N/A

Attack Vector

Local

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Attack Vector

Local

Attack Complexity

High

Authentication

None

Confidentiality

None

Integrity

None

Availability

Complete

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2022-07-21 CVE Reserved
2022-07-21 CVE Published
2024-08-04 CVE Updated
2025-04-15 EPSS Updated
---------- Exploited in Wild
---------- KEV Due Date
---------- First Exploit

CWE

CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
CWE-416: Use After Free

CAPEC

References (4)

URL	Tag	Source

URL	Date	SRC

URL	Date	SRC
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.6.2	2022-07-27
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ca4463bf8438b403596edd0ec961ca0d4fbe0220	2022-07-27

URL	Date	SRC
https://access.redhat.com/security/cve/CVE-2020-36557	2021-05-18
https://bugzilla.redhat.com/show_bug.cgi?id=2112688	2021-05-18

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				< 5.6.2 Search vendor "Linux" for product "Linux Kernel" and version " < 5.6.2"		-		Affected