#VU104502 Use-after-free in Linux kernel - CVE-2021-47634

Cybersecurity Help s.r.o.

Published: 2025-02-26 | Updated: 2025-05-11

Vulnerability identifier: #VU104502

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-2021-47634

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 escalate privileges on the system.

The vulnerability exists due to a use-after-free error within the vol_attribute_show() function in drivers/mtd/ubi/vmt.c, within the dev_attribute_show(), ubi_attach_mtd_dev() and uif_close() functions in drivers/mtd/ubi/build.c. A local user can escalate privileges on the system.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Linux kernel: 4.14, 4.14.0, 4.14.0 rc1, 4.14.1, 4.14.2, 4.14.3, 4.14.4, 4.14.5, 4.14.6, 4.14.7, 4.14.8, 4.14.9, 4.14.10, 4.14.11, 4.14.12, 4.14.13, 4.14.14, 4.14.15, 4.14.16, 4.14.17, 4.14.18, 4.14.19, 4.14.20, 4.14.21, 4.14.22, 4.14.23, 4.14.24, 4.14.25, 4.14.26, 4.14.27, 4.14.28, 4.14.29, 4.14.30, 4.14.31, 4.14.32, 4.14.33, 4.14.34, 4.14.35, 4.14.36, 4.14.37, 4.14.38, 4.14.39, 4.14.40, 4.14.41, 4.14.42, 4.14.43, 4.14.44, 4.14.45, 4.14.46, 4.14.47, 4.14.48, 4.14.49, 4.14.50, 4.14.51, 4.14.52, 4.14.53, 4.14.54, 4.14.55, 4.14.56, 4.14.57, 4.14.58, 4.14.59, 4.14.60, 4.14.61, 4.14.62, 4.14.63, 4.14.64, 4.14.65, 4.14.66, 4.14.67, 4.14.68, 4.14.69, 4.14.70, 4.14.71, 4.14.72, 4.14.73, 4.14.74, 4.14.75, 4.14.76, 4.14.77, 4.14.78, 4.14.79, 4.14.80, 4.14.81, 4.14.82, 4.14.83, 4.14.84, 4.14.85, 4.14.86, 4.14.87, 4.14.88, 4.14.89, 4.14.90, 4.14.91, 4.14.92, 4.14.93, 4.14.94, 4.14.95, 4.14.96, 4.14.97, 4.14.98, 4.14.99, 4.14.100, 4.14.101, 4.14.102, 4.14.103, 4.14.104, 4.14.105, 4.14.106, 4.14.107, 4.14.108, 4.14.109, 4.14.110, 4.14.111, 4.14.112, 4.14.113, 4.14.114, 4.14.115, 4.14.116, 4.14.117, 4.14.118, 4.14.119, 4.14.120, 4.14.121, 4.14.122, 4.14.123, 4.14.124, 4.14.125, 4.14.126, 4.14.127, 4.14.128, 4.14.129, 4.14.130, 4.14.131, 4.14.132, 4.14.133, 4.14.134, 4.14.135, 4.14.136, 4.14.137, 4.14.138, 4.14.139, 4.14.140, 4.14.141, 4.14.142, 4.14.143, 4.14.144, 4.14.145, 4.14.146, 4.14.147, 4.14.148, 4.14.149, 4.14.150, 4.14.151, 4.14.152, 4.14.153, 4.14.154, 4.14.155, 4.14.156, 4.14.157, 4.14.158, 4.14.159, 4.14.160, 4.14.161, 4.14.162, 4.14.163, 4.14.164, 4.14.165, 4.14.166, 4.14.167, 4.14.168, 4.14.169, 4.14.170, 4.14.171, 4.14.172, 4.14.173, 4.14.174, 4.14.175, 4.14.176, 4.14.177, 4.14.178, 4.14.179, 4.14.180, 4.14.181, 4.14.182, 4.14.183, 4.14.184, 4.14.185, 4.14.186, 4.14.187, 4.14.188, 4.14.189, 4.14.190, 4.14.191, 4.14.192, 4.14.193, 4.14.194, 4.14.195, 4.14.196, 4.14.197, 4.14.198, 4.14.199, 4.14.200, 4.14.201, 4.14.202, 4.14.203, 4.14.204, 4.14.205, 4.14.206, 4.14.207, 4.14.208, 4.14.209, 4.14.210, 4.14.211, 4.14.212, 4.14.213, 4.14.214, 4.14.215, 4.14.216, 4.14.217, 4.14.218, 4.14.219, 4.14.220, 4.14.221, 4.14.222, 4.14.223, 4.14.224, 4.14.225, 4.14.226, 4.14.227, 4.14.228, 4.14.229, 4.14.230, 4.14.231, 4.14.232, 4.14.233, 4.14.234, 4.14.235, 4.14.236, 4.14.237, 4.14.238, 4.14.239, 4.14.240, 4.14.241, 4.14.242, 4.14.243, 4.14.244, 4.14.245, 4.14.246, 4.14.247, 4.14.248, 4.14.249, 4.14.250, 4.14.251, 4.14.252, 4.14.253, 4.14.254, 4.14.255, 4.14.256, 4.14.257, 4.14.258, 4.14.259, 4.14.260, 4.14.261, 4.14.262, 4.14.263, 4.14.264, 4.14.265, 4.14.266, 4.14.267, 4.14.268, 4.14.269, 4.14.270, 4.14.271, 4.14.272, 4.14.273, 4.14.274, 4.14.275

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.

Latest bulletins with this vulnerability

openEuler 20.03 LTS SP4 update for kernel

SUSE update for the Linux Kernel

Use-after-free in Linux kernel mtd ubi driver