Privilege escalation in Linux kernel



Published: 2021-07-22
Risk Low
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2021-33033
CWE-ID CWE-416
Exploitation vector Local
Public exploit N/A
Vulnerable software
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Linux kernel
Operating systems & Components / Operating system

Vendor

Security Bulletin

This security bulletin contains one low risk vulnerability.

1) Use-after-free

EUVDB-ID: #VU55261

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-2021-33033

CWE-ID: CWE-416 - Use After Free

Exploit availability: No

Description

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.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Linux kernel: before 5.11.4

External links

http://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ad5d07f4a9cd671233ae20983848874731102c08
http://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.14
http://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.11.7
http://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1165affd484889d4986cf3b724318935a0b120d8
http://sites.google.com/view/syzscope/kasan-use-after-free-read-in-cipso_v4_genopt
http://syzkaller.appspot.com/bug?id=96e7d345748d8814901c91cd92084ed04b46701e


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.



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