HIGH

CVE-2018-18955

CVSS v3

7

HIGH

EPSS Score

12.2%

exploit probability

CISA KEV

No

known exploited

Exploitation

SSVC status

Description

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.

Technical details

Published
11/16/2018

Frequently asked questions

What is 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 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.

Is CVE-2018-18955 actively exploited?

Active exploitation of CVE-2018-18955 has not been confirmed. The EPSS score is 12.2%, indicating the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2018-18955?

CVE-2018-18955 has a CVSS v3 base score of 7 (HIGH severity).

Is CVE-2018-18955 affecting your environment?

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