Privilege escalation in Linux kernel

1) Use-after-free

EUVDB-ID: #VU83585

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-2020-25220

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 skcd->no_refcnt was not considered during a backport of a patch for #VU49669 (CVE-2020-14356). A local user can trigger a use-after-free error and escalate privileges on the system.

Mitigation

Install update from vendor's website.

Vulnerable software versions

Linux kernel: 4.9 - 4.19.139

External links

http://bugzilla.redhat.com/show_bug.cgi?id=1868453
http://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.14.194
http://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.19.140
http://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.9.233
http://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.14.y&id=82fd2138a5ffd7e0d4320cdb669e115ee976a26e
http://lists.debian.org/debian-lts-announce/2020/10/msg00032.html
http://lists.debian.org/debian-lts-announce/2020/10/msg00034.html
http://security.netapp.com/advisory/ntap-20201001-0004/
http://www.spinics.net/lists/stable/msg405099.html

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.