Vulnerability identifier: #VU66590

Vulnerability risk: Low

CVSSv3.1: 6.8 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-33656

CWE-ID: CWE-787

Exploitation vector: Local

Exploit availability: No

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

Vendor:

Description

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

The vulnerability exists due to a boundary error when setting font with malicous data by ioctl cmd PIO_FONT. A local user can trigger an out-of-bounds write and execute arbitrary code with elevated privileges.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

---

External links
http://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git/tree/releases/5.10.127/vt-drop-old-font-ioctls.patch
http://www.openeuler.org/en/security/cve/detail.html?id=CVE-2021-33656&packageName=kernel
http://www.openwall.com/lists/oss-security/2022/07/19/3

---

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.