Debian update for linux

Published: 2021-07-22 | Updated: 2022-08-09

Risk	Medium
Patch available	YES
Number of vulnerabilities	4
CVE-ID	CVE-2020-36311 CVE-2021-3609 CVE-2021-33909 CVE-2021-34693
CWE-ID	CWE-264 CWE-362 CWE-190 CWE-908
Exploitation vector	Local
Public exploit	Public exploit code for vulnerability #2 is available. Public exploit code for vulnerability #3 is available.
Vulnerable software	linux (Debian package) Operating systems & Components / Operating system package or component
Vendor	Debian

Security Bulletin

This security bulletin contains information about 4 vulnerabilities.

1) Permissions, Privileges, and Access Controls

EUVDB-ID: #VU55262

Risk: Low

CVSSv4.0: 4.3 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2020-36311

CWE-ID: CWE-264 - Permissions, Privileges, and Access Controls

Exploit availability: No

Description

The vulnerability allows a local user to perform a denial of service attack.

The vulnerability exists due to an error in arch/x86/kvm/svm/sev.c in Linux kernel, which allows soft lockup by triggering destruction of a large SEV VM (which requires unregistering many encrypted regions).

Mitigation

Update linux package to version 4.19.194-3.

Vulnerable software versions

linux (Debian package): 4.19.5-1~exp1 - 4.19.160-2

CPE2.3

External links

https://www.debian.org/security/2021/dsa-4941

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.

2) Race condition

EUVDB-ID: #VU54292

Risk: Medium

CVSSv4.0: 7.1 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2021-3609

CWE-ID: CWE-362 - Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Exploit availability: No

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a race condition in the CAN BCM networking protocol (net/can/bcm.c) in the Linux kernel ranging from version 2.6.25 to mainline 5.13-rc6. A local user can exploit the race and gain unauthorized access to sensitive information and escalate privileges on the system.

Mitigation

Update linux package to version 4.19.194-3.

Vulnerable software versions

linux (Debian package): 4.19.5-1~exp1 - 4.19.160-2

CPE2.3

External links

https://www.debian.org/security/2021/dsa-4941

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.

3) Integer overflow

EUVDB-ID: #VU55143

Risk: Low

CVSSv4.0: 7.1 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/U:Clear]

CVE-ID: CVE-2021-33909

CWE-ID: CWE-190 - Integer overflow

Exploit availability: Yes

Description

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to integer overflow during size_t-to-int conversion when creating, mounting, and deleting a deep directory structure whose total path length exceeds 1GB. An unprivileged local user can write up to 10-byte string to an offset of exactly -2GB-10B below the beginning of a vmalloc()ated kernel buffer.

Successful exploitation of vulnerability may allow an attacker to exploit the our-of-bounds write vulnerability to execute arbitrary code with root privileges.

Mitigation

Update linux package to version 4.19.194-3.

Vulnerable software versions

linux (Debian package): 4.19.5-1~exp1 - 4.19.160-2

CPE2.3

External links

https://www.debian.org/security/2021/dsa-4941

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.

4) Use of uninitialized resource

EUVDB-ID: #VU55263

Risk: Low

CVSSv4.0: 1.1 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2021-34693

CWE-ID: CWE-908 - Use of Uninitialized Resource

Exploit availability: No

Description

The vulnerability allows a local user to gain access to sensitive information.

The vulnerability exists due to net/can/bcm.c in the Linux kernel through 5.12.10 allows local users to obtain sensitive information from kernel stack memory because parts of a data structure are uninitialized.

Mitigation

Update linux package to version 4.19.194-3.

Vulnerable software versions

linux (Debian package): 4.19.5-1~exp1 - 4.19.160-2

CPE2.3

External links

https://www.debian.org/security/2021/dsa-4941

Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.