Linux Kernel expand_downwards Function NULL Pointer Dereference Vulnerability [CVE-2019-9213]

CVE Number – CVE-2019-9213

A vulnerability in the Linux Kernel could allow an unauthenticated, local attacker to cause a denial of service (DoS) condition on the targeted system.The vulnerability exists in the expand_downwards function, as defined in the mm/mmap.c source code of the Linux Kernel, which does not provide adequate checking for the mmap minimum address. An attacker could exploit this vulnerability by supplying invalid data to the affected system, causing a NULL pointer dereference on the Linux Kernel. A successful exploit could allow the attacker to cause a DoS condition on the targeted system.Proof-of-concept (PoC) code that demonstrates an exploit of this vulnerability is publicly has confirmed the vulnerability and released software updates.


  • To exploit this vulnerability an attacker must have local access to the targeted system. This requirement could reduce the likelihood of a successful exploit.


  • Administrators are advised to apply the appropriate updates.Administrators are advised to allow only trusted users to access local systems.Administrators are advised to allow only privileged users to access administration or management systems.Administrators are advised to monitor critical systems.

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Duncan Newell

Duncan is a technology professional with over 20 years experience of working in various IT roles. He has a interest in cyber security, and has a wide range of other skills in radio, electronics and telecommunications.

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