#VU89391 Double Free in Linux kernel - CVE-2021-47082

Vulnerability identifier: #VU89391

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-2021-47082

CWE-ID: CWE-415

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 boundary error in drivers/net/tun.c. A local user can trigger a double free error and execute arbitrary code with elevated privileges.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Linux kernel: 4.19, 4.19.1, 4.19.2, 4.19.3, 4.19.4, 4.19.5, 4.19.6, 4.19.7, 4.19.8, 4.19.9, 4.19.10, 4.19.11, 4.19.12, 4.19.13, 4.19.14, 4.19.15, 4.19.16, 4.19.17, 4.19.18, 4.19.19, 4.19.20, 4.19.21, 4.19.22, 4.19.23, 4.19.24, 4.19.25, 4.19.26, 4.19.27, 4.19.28, 4.19.29, 4.19.30, 4.19.31, 4.19.32, 4.19.33, 4.19.34, 4.19.35, 4.19.36, 4.19.37, 4.19.38, 4.19.39, 4.19.40, 4.19.41, 4.19.42, 4.19.43, 4.19.44, 4.19.45, 4.19.46, 4.19.47, 4.19.48, 4.19.49, 4.19.50, 4.19.51, 4.19.52, 4.19.53, 4.19.54, 4.19.55, 4.19.56, 4.19.57, 4.19.58, 4.19.59, 4.19.60, 4.19.61, 4.19.62, 4.19.63, 4.19.64, 4.19.65, 4.19.66, 4.19.67, 4.19.68, 4.19.69, 4.19.70, 4.19.71, 4.19.72, 4.19.73, 4.19.74, 4.19.75, 4.19.76, 4.19.77, 4.19.78, 4.19.79, 4.19.80, 4.19.81, 4.19.82, 4.19.83, 4.19.84, 4.19.85, 4.19.86, 4.19.87, 4.19.88, 4.19.89, 4.19.90, 4.19.91, 4.19.92, 4.19.93, 4.19.94, 4.19.95, 4.19.96, 4.19.97, 4.19.98, 4.19.99, 4.19.100, 4.19.101, 4.19.102, 4.19.103, 4.19.104, 4.19.105, 4.19.106, 4.19.107, 4.19.108, 4.19.109, 4.19.110, 4.19.111, 4.19.112, 4.19.113, 4.19.114, 4.19.115, 4.19.116, 4.19.117, 4.19.118, 4.19.118-2, 4.19.119, 4.19.120, 4.19.121, 4.19.122, 4.19.123, 4.19.124, 4.19.125, 4.19.126, 4.19.127, 4.19.128, 4.19.129, 4.19.130, 4.19.131, 4.19.132, 4.19.133, 4.19.134, 4.19.135, 4.19.136, 4.19.137, 4.19.138, 4.19.139, 4.19.140, 4.19.141, 4.19.142, 4.19.143, 4.19.144, 4.19.145, 4.19.146, 4.19.147, 4.19.148, 4.19.149, 4.19.150, 4.19.151, 4.19.152, 4.19.153, 4.19.154, 4.19.155, 4.19.156, 4.19.157, 4.19.158, 4.19.159, 4.19.160, 4.19.161, 4.19.162, 4.19.163, 4.19.164, 4.19.165, 4.19.166, 4.19.167, 4.19.168, 4.19.169, 4.19.170, 4.19.171, 4.19.172, 4.19.173, 4.19.174, 4.19.175, 4.19.176, 4.19.177, 4.19.178, 4.19.179, 4.19.180, 4.19.181, 4.19.182, 4.19.183, 4.19.184, 4.19.185, 4.19.186, 4.19.187, 4.19.188, 4.19.189, 4.19.190, 4.19.191, 4.19.192, 4.19.193, 4.19.194, 4.19.195, 4.19.196, 4.19.197, 4.19.198, 4.19.199, 4.19.200, 4.19.201, 4.19.202, 4.19.203, 4.19.204, 4.19.205, 4.19.206, 4.19.207, 4.19.208, 4.19.209, 4.19.210, 4.19.211, 4.19.212, 4.19.213, 4.19.214, 4.19.215, 4.19.216, 4.19.217, 4.19.218, 4.19.219, 4.19.220, 4.19.221, 4.19.222, 4.19.223, 4.19.224, 4.19.225, 4.19.226, 4.19.227, 4.19.228, 4.19.229, 4.19.230, 4.19.231, 4.19.232, 4.19.233, 4.19.234, 4.19.235, 4.19.236, 4.19.237, 4.19.238, 4.19.239, 4.19.240, 4.19.241, 4.19.242, 4.19.243, 4.19.244, 4.19.245, 4.19.246, 4.19.247, 4.19.248, 4.19.249, 4.19.250, 4.19.251, 4.19.252, 4.19.253, 4.19.254, 4.19.255, 4.19.256, 4.19.257, 4.19.258, 4.19.259, 4.19.260, 4.19.261, 4.19.262, 4.19.263, 4.19.264, 4.19.265, 4.19.266, 4.19.267, 4.19.268, 4.19.269, 4.19.270, 4.19.271, 4.19.272, 4.19.273, 4.19.274, 4.19.275, 4.19.276, 4.19.277, 4.19.278, 4.19.279, 5.4, 5.4.0, 5.4.0 rc6, 5.4.1, 5.4.2, 5.4.3, 5.4.4, 5.4.5, 5.4.6, 5.4.7, 5.4.8, 5.4.9, 5.4.10, 5.4.11, 5.4.12, 5.4.13, 5.4.14, 5.4.15, 5.4.16, 5.4.17, 5.4.18, 5.4.19, 5.4.20, 5.4.21, 5.4.22, 5.4.23, 5.4.24, 5.4.25, 5.4.26, 5.4.27, 5.4.28, 5.4.29, 5.4.30, 5.4.31, 5.4.32, 5.4.33, 5.4.34, 5.4.35, 5.4.36, 5.4.37, 5.4.38, 5.4.39, 5.4.40, 5.4.41, 5.4.42, 5.4.43, 5.4.44, 5.4.45, 5.4.46, 5.4.47, 5.4.48, 5.4.49, 5.4.50, 5.4.51, 5.4.52, 5.4.53, 5.4.54, 5.4.55, 5.4.56, 5.4.57, 5.4.58, 5.4.59, 5.4.60, 5.4.61, 5.4.62, 5.4.63, 5.4.64, 5.4.65, 5.4.66, 5.4.67, 5.4.68, 5.4.69, 5.4.70, 5.4.71, 5.4.72, 5.4.73, 5.4.74, 5.4.75, 5.4.76, 5.4.77, 5.4.78, 5.4.79, 5.4.80, 5.4.81, 5.4.82, 5.4.83, 5.4.84, 5.4.85, 5.4.86, 5.4.87, 5.4.88, 5.4.89, 5.4.90, 5.4.91, 5.4.92, 5.4.93, 5.4.94, 5.4.95, 5.4.96, 5.4.97, 5.4.98, 5.4.99, 5.4.100, 5.4.101, 5.4.102, 5.4.103, 5.4.104, 5.4.105, 5.4.106, 5.4.107, 5.4.108, 5.4.109, 5.4.110, 5.4.111, 5.4.112, 5.4.113, 5.4.114, 5.4.115, 5.4.116, 5.4.117, 5.4.118, 5.4.119, 5.4.120, 5.4.121, 5.4.122, 5.4.123, 5.4.124, 5.4.125, 5.4.126, 5.4.127, 5.4.128, 5.4.129, 5.4.130, 5.4.131, 5.4.132, 5.4.133, 5.4.134, 5.4.135, 5.4.136, 5.4.137, 5.4.138, 5.4.139, 5.4.140, 5.4.141, 5.4.142, 5.4.143, 5.4.144, 5.4.145, 5.4.146, 5.4.147, 5.4.148, 5.4.149, 5.4.150, 5.4.151, 5.4.152, 5.4.153, 5.4.154, 5.4.155, 5.4.156, 5.4.157, 5.4.158, 5.4.159, 5.4.160, 5.4.161, 5.4.162, 5.4.163, 5.4.164, 5.4.165, 5.4.166, 5.4.167, 5.4.168, 5.4.169, 5.4.170, 5.4.171, 5.4.172, 5.4.173, 5.4.174, 5.4.175, 5.4.176, 5.4.177, 5.4.178, 5.4.179, 5.4.180, 5.4.181, 5.4.182, 5.4.183, 5.4.184, 5.4.185, 5.4.186, 5.4.187, 5.4.188, 5.4.189, 5.4.190, 5.4.191, 5.4.192, 5.4.193, 5.4.194, 5.4.195, 5.4.196, 5.4.197, 5.4.198, 5.4.199, 5.4.200, 5.4.201, 5.4.202, 5.4.203, 5.4.204, 5.4.205, 5.4.206, 5.4.207, 5.4.208, 5.4.209, 5.4.210, 5.4.211, 5.4.212, 5.4.213, 5.4.214, 5.4.215, 5.4.216, 5.4.217, 5.4.218, 5.4.219, 5.4.220, 5.4.221, 5.4.222, 5.4.223, 5.4.224, 5.4.225, 5.4.226, 5.4.227, 5.4.228, 5.4.229, 5.4.230, 5.4.231, 5.4.232, 5.4.233, 5.4.234, 5.4.235, 5.4.236, 5.4.237, 5.4.238, 5.4.239, 5.10, 5.10 rc1, 5.10 rc2, 5.10 rc3, 5.10 rc4, 5.10 rc5, 5.10 rc7, 5.10.1, 5.10.2, 5.10.3, 5.10.4, 5.10.5, 5.10.6, 5.10.7, 5.10.8, 5.10.9, 5.10.10, 5.10.11, 5.10.12, 5.10.13, 5.10.14, 5.10.15, 5.10.16, 5.10.17, 5.10.18, 5.10.19, 5.10.20, 5.10.21, 5.10.22, 5.10.23, 5.10.24, 5.10.25, 5.10.26, 5.10.27, 5.10.28, 5.10.29, 5.10.30, 5.10.31, 5.10.32, 5.10.33, 5.10.34, 5.10.35, 5.10.36, 5.10.37, 5.10.38, 5.10.39, 5.10.40, 5.10.41, 5.10.42, 5.10.43, 5.10.44, 5.10.45, 5.10.46, 5.10.47, 5.10.48, 5.10.49, 5.10.50, 5.10.51, 5.10.52, 5.10.53, 5.10.54, 5.10.55, 5.10.56, 5.10.57, 5.10.58, 5.10.59, 5.10.60, 5.10.61, 5.10.62, 5.10.63, 5.10.64, 5.10.65, 5.10.66, 5.10.67, 5.10.68, 5.10.69, 5.10.70, 5.10.71, 5.10.72, 5.10.73, 5.10.74, 5.10.75, 5.10.76, 5.10.77, 5.10.78, 5.10.79, 5.10.80, 5.10.81, 5.10.82, 5.10.83, 5.10.84, 5.10.85, 5.10.86, 5.10.87, 5.10.88, 5.10.89, 5.10.90, 5.10.91, 5.10.92, 5.10.93, 5.10.94, 5.10.95, 5.10.96, 5.10.97, 5.10.98, 5.10.99, 5.10.100, 5.10.101, 5.10.102, 5.10.103, 5.10.104, 5.10.105, 5.10.106, 5.10.107, 5.10.108, 5.10.109, 5.10.110, 5.10.111, 5.10.112, 5.10.113, 5.10.114, 5.10.115, 5.10.116, 5.10.117, 5.10.118, 5.10.119, 5.10.120, 5.10.121, 5.10.122, 5.10.123, 5.10.124, 5.10.125, 5.10.126, 5.10.127, 5.10.128, 5.10.129, 5.10.130, 5.10.131, 5.10.132, 5.10.133, 5.10.134, 5.10.135, 5.15, 5.15 rc1, 5.15 rc2, 5.15 rc3, 5.15 rc4, 5.15 rc5, 5.15 rc6, 5.15 rc7, 5.15.0, 5.15.1, 5.15.2, 5.15.3, 5.15.4, 5.15.5, 5.15.6, 5.15.7, 5.15.8, 5.15.9, 5.15.10, 5.15.11, 5.16 rc1, 5.16 rc2, 5.16 rc3, 5.16 rc4, 5.16 rc5, 5.16 rc6, 5.16 rc8

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External links
https://git.kernel.org/stable/c/8eb43d635950e27c29f1e9e49a23b31637f37757
https://git.kernel.org/stable/c/0c0e566f0387490d16f166808c72e9c772027681
https://git.kernel.org/stable/c/a01a4e9f5dc93335c716fa4023b1901956e8c904
https://git.kernel.org/stable/c/3cb5ae77799e8ed6ec3fec0b6b4cd07f01650cc5
https://git.kernel.org/stable/c/158b515f703e75e7d68289bf4d98c664e1d632df
https://mirrors.edge.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.19.280
https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.10.136
https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.15.12
https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.16
https://mirrors.edge.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.4.240

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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.