#VU57039 Improper locking in Linux kernel - CVE-2020-29660

Vulnerability identifier: #VU57039

Vulnerability risk: Low

CVSSv4.0: 4 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2020-29660

CWE-ID: CWE-667

Exploitation vector: Local

Exploit availability: No

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

Vendor: Linux Foundation

Description

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

The vulnerability exists due to double-locking error in drivers/tty/tty_io.c and drivers/tty/tty_jobctrl.c. An authenticated local user can exploit this vulnerability to perform a read-after-free attack against TIOCGSID and gain access to sensitive information.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Linux kernel: before 5.9.14, 5.9.14

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External links
https://www.openwall.com/lists/oss-security/2020/12/10/1
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=c8bcd9c5be24fb9e6132e97da5a35e55a83e36b9
https://lists.debian.org/debian-lts-announce/2021/02/msg00018.html
https://lists.debian.org/debian-lts-announce/2021/03/msg00010.html
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/BOB25SU6XUL4TNP7KB63WNZSYTIYFDPP/
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/MZ7OAKAEFAXQRGBZK4LYUWINCD3D2XCL/
https://security.netapp.com/advisory/ntap-20210122-0001/
https://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.