#VU92762 Use after free in Linux kernel - CVE-2020-25669

Vulnerability identifier: #VU92762

Vulnerability risk: Low

CVSSv4.0: 5.9 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear]

CVE-ID: CVE-2020-25669

CWE-ID: CWE-416

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 execute arbitrary code.

A vulnerability was found in the Linux Kernel where the function sunkbd_reinit having been scheduled by sunkbd_interrupt before sunkbd being freed. Though the dangling pointer is set to NULL in sunkbd_disconnect, there is still an alias in sunkbd_reinit causing Use After Free.

Mitigation
Install update from vendor's repository.

Vulnerable software versions

Linux kernel: All versions

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External links
https://github.com/torvalds/linux/commit/77e70d351db7de07a46ac49b87a6c3c7a60fca7e
https://lists.debian.org/debian-lts-announce/2020/12/msg00027.html
https://www.openwall.com/lists/oss-security/2020/11/20/5
https://lists.debian.org/debian-lts-announce/2020/12/msg00015.html
https://www.openwall.com/lists/oss-security/2020/11/05/2
https://www.openwall.com/lists/oss-security/2020/11/05/2,
https://www.openwall.com/lists/oss-security/2020/11/20/5,
https://security.netapp.com/advisory/ntap-20210702-0006/

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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.