#VU63574 Out-of-bounds write in Linux kernel - CVE-2021-31916

Vulnerability identifier: #VU63574

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-2021-31916

CWE-ID: CWE-787

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 escalate privileges on the system.

The vulnerability exists due to a boundary error in list_devices in drivers/md/dm-ioctl.c in the Multi-device driver module. A special user (CAP_SYS_ADMIN) can trigger a buffer overflow in the ioctl for listing devices and escalate privileges on the system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Linux kernel: 5.0 - 5.0.21, 5.1 rc5 - 5.11.21, 5.2 - 5.2.21, 5.3 - 5.3.18, 5.4 - 5.4.99, 5.5 - 5.5.19, 5.6 - 5.6.14, 5.7 - 5.7.10, 5.8 rc6 - 5.8.17, 5.9 rc7 - 5.9.16

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External links
https://seclists.org/oss-sec/2021/q1/268
https://bugzilla.redhat.com/show_bug.cgi?id=1946965
https://github.com/torvalds/linux/commit/4edbe1d7bcffcd6269f3b5eb63f710393ff2ec7a
https://lists.debian.org/debian-lts-announce/2021/06/msg00019.html
https://lists.debian.org/debian-lts-announce/2021/06/msg00020.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.