#VU63766 Double Free in Linux kernel - CVE-2021-22600

Vulnerability identifier: #VU63766

Vulnerability risk: High

CVSSv4.0: 8.5 [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:A/U:Amber]

CVE-ID: CVE-2021-22600

CWE-ID: CWE-415

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 packet_set_ring() function in net/packet/af_packet.c. A local user can pass specially crafted data to the application, trigger double free error and escalate privileges on the system.

Note, the vulnerability is being actively exploited in the wild against Android users.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Linux kernel: before 5.16, 5.16

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External links
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit?id=ec6af094ea28f0f2dda1a6a33b14cd57e36a9755
https://www.debian.org/security/2022/dsa-5096
https://lists.debian.org/debian-lts-announce/2022/03/msg00012.html
https://bugzilla.redhat.com/show_bug.cgi?id=2047912

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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?

Yes. This vulnerability is being exploited in the wild.