#VU21255 Out-of-bounds write in Linux kernel - CVE-2019-14821

Vulnerability identifier: #VU21255

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-2019-14821

CWE-ID: CWE-787

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 the KVM coalesced MMIO support functionality due to incorrect processing of shared indexes. A local user can run a specially crafted application to trigger an out-of-bounds write error and write data to arbitrary address in the kernel memory.

Successful vulnerability exploitation may allow an attacker to execute arbitrary code on the system with root privileges.

Mitigation
Install updates from vendor's repository.

Vulnerable software versions

Linux kernel: 4.4.0 - 4.4.193, 4.9 - 4.9.193, 4.14.0 rc1 - 4.19.74, 5.0 - 5.0.21, 5.1 rc1 - 5.1.21, 5.2 - 5.2.21, 5.3 - 5.3.13

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External links
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.3.1
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.2.17
https://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.9.194
https://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.4.194
https://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.19.75
https://www.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.14.146
https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.4

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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.