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high7.0Public exploit code

CVE-2018-18955

In the Linux kernel 4.15.x through 4.19.x before 4.19.2, map_write() in kernel/user_namespace.c allows privilege escalation because it mishandles nested user n…

Public exploit code

Working exploit or proof of concept code has been published for this vulnerability. Treat unpatched systems as at risk.

Impact

In the Linux kernel 4.15.x through 4.19.x before 4.19.2, map_write() in kernel/user_namespace.c allows privilege escalation because it mishandles nested user namespaces with more than 5 UID or GID ranges. A user who has CAP_SYS_ADMIN in an affected user namespace can bypass access controls on resources outside the namespace, as demonstrated by reading /etc/shadow. This occurs because an ID transformation takes place properly for the namespaced-to-kernel direction but not for the kernel-to-namespaced direction.

Affected products

VendorProductAffected versions
LinuxLinux Kernel
from 4.15 before 4.19.2
CanonicalUbuntu Linux
Versions 16.04, 18.04, 18.10

Weakness classification

CWE-863

References