#VU63669 Out-of-bounds write in Linux kernel - CVE-2021-42008

Vulnerability identifier: #VU63669

Vulnerability risk: Low

CVSSv4.0: 7 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:P/U:Clear]

CVE-ID: CVE-2021-42008

CWE-ID: CWE-787

Exploitation vector: Local

Exploit availability: Yes

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

Vendor: Linux Foundation

Description

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

The vulnerability exists due to a boundary error in the decode_data() function in drivers/net/hamradio/6pack.c in the Linux kernel. A local user can send input from a process that has the CAP_NET_ADMIN capability and escalate privileges on the system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Linux kernel: 5.13 rc1 - 5.13.14

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External links
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=19d1532a187669ce86d5a2696eb7275310070793
https://www.youtube.com/watch?v=d5f9xLK8Vhw
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.13.13
https://security.netapp.com/advisory/ntap-20211104-0002/
https://lists.debian.org/debian-lts-announce/2021/12/msg00012.html

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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. However, proof of concept for this vulnerability is available.