Vulnerability identifier: #VU51543

Vulnerability risk: Low

CVSSv3.1: 6.8 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-29661

CWE-ID: CWE-667

Exploitation vector: Local

Exploit availability: No

Vulnerable software:
Linux kernel
Operating systems & Components / Operating system

Vendor:

Description

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

The vulnerability exists due to locking error in the tty subsystem of the Linux kernel in drivers/tty/tty_jobctrl.c. An local user can exploit this vulnerability to trigger a use-after-free error against TIOCSPGRP and execute arbitrary code with elevated privileges.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

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External links
http://packetstormsecurity.com/files/160681/Linux-TIOCSPGRP-Broken-Locking.html
http://www.openwall.com/lists/oss-security/2020/12/10/1
http://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=54ffccbf053b5b6ca4f6e45094b942fab92a25fc
http://lists.debian.org/debian-lts-announce/2021/02/msg00018.html
http://lists.debian.org/debian-lts-announce/2021/03/msg00010.html
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/BOB25SU6XUL4TNP7KB63WNZSYTIYFDPP/
http://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/MZ7OAKAEFAXQRGBZK4LYUWINCD3D2XCL/
http://security.netapp.com/advisory/ntap-20210122-0001/
http://www.debian.org/security/2021/dsa-4843

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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.