#VU63662 Use-after-free in Linux kernel - CVE-2021-3573

Vulnerability identifier: #VU63662

Vulnerability risk: Low

CVSSv4.0: 5.7 [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:U/U:Clear]

CVE-ID: CVE-2021-3573

CWE-ID: CWE-416

Exploitation vector: Local

Exploit availability: No

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

Vendor: Linux Foundation

Description

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

The vulnerability exists due to a use-after-free in hci_sock_bound_ioctl() function of the Linux kernel HCI subsystem triggers race condition of the call hci_unregister_dev() together with one of the calls hci_sock_blacklist_add(), hci_sock_blacklist_del(), hci_get_conn_info(), hci_get_auth_info(). A privileged local user can use this flaw to crash the system or escalate privileges on the system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Linux kernel: before 5.13, 5.13

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External links
https://bugzilla.redhat.com/show_bug.cgi?id=1966578
https://git.kernel.org/pub/scm/linux/kernel/git/bluetooth/bluetooth.git/commit/?id=e305509e678b3a4af2b3cfd410f409f7cdaabb52
https://www.openwall.com/lists/oss-security/2021/06/08/2

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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.