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Linux Nested User Namespace idmap Limit Local Privilege Escalation

This module exploits a vulnerability in Linux kernels 4.15.0 to 4.18.18, and 4.19.0 to 4.19.1, where broken uid/gid mappings between nested user namespaces and kernel uid/gid mappings allow elevation to root (CVE-2018-18955). The target system must have unprivileged user namespaces enabled and the newuidmap and newgidmap helpers installed (from uidmap package). This module has been tested successfully on: Fedora Workstation 28 kernel 4.16.3-301.fc28.x86_64; Kubuntu 18.04 LTS kernel 4.15.0-20-generic (x86_64); Linux Mint 19 kernel 4.15.0-20-generic (x86_64); Ubuntu Linux 18.04.1 LTS kernel 4.15.0-20-generic (x86_64).

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Module Name



  • Jann Horn
  • bcoles <bcoles [at]>



  • Auto


  • linux


  • x86
  • x64



Module Options

To display the available options, load the module within the Metasploit console and run the commands 'show options' or 'show advanced':

msf > use exploit/linux/local/nested_namespace_idmap_limit_priv_esc msf exploit(nested_namespace_idmap_limit_priv_esc) > show targets ...targets... msf exploit(nested_namespace_idmap_limit_priv_esc) > set TARGET <target-id> msf exploit(nested_namespace_idmap_limit_priv_esc) > show options and set options... msf exploit(nested_namespace_idmap_limit_priv_esc) > exploit

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