Privilege escalation in Linux kernel

Published: 2021-07-22
Risk Low
Patch available YES
Number of vulnerabilities 1
CVE ID CVE-2021-33033
Exploitation vector Local
Public exploit N/A
Vulnerable software
Linux kernel
Operating systems & Components / Operating system


Security Advisory

This security advisory describes one low risk vulnerability.

1) Use-after-free

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] [PCI]

CVE-ID: CVE-2021-33033

CWE-ID: CWE-416 - Use After Free

Exploit availability: No


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

The vulnerability exists due to improper handling of the CIPSO and CALIPSO refcounting for the DOI definitions in cipso_v4_genopt(0 function in net/ipv4/cipso_ipv4.c in Linux kernel. A local user can trigger a use-after-free error and execute arbitrary code with escalated privileges.


Install updates from vendor's website.

Vulnerable software versions

Linux kernel: before 5.11.4

CPE External links

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.