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.
:heavy_check_mark: This issue was automatically closed by Mend because the vulnerable library in the specific branch(es) was either marked as ignored or it is no longer part of the Mend inventory.
CVE-2018-18955 - High Severity Vulnerability
Vulnerable Library - linuxlinux-4.1.18
Apache Software Foundation (ASF)
Library home page: https://mirrors.edge.kernel.org/pub/linux/kernel/v4.x/?wsslib=linux
Found in HEAD commit: 9cafd1b39d091c76656512d15c90a6952f088074
Found in base branch: master
Vulnerable Source Files (2)
/kernel/user_namespace.c /kernel/user_namespace.c
Vulnerability Details
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.
Publish Date: 2018-11-16
URL: CVE-2018-18955
CVSS 3 Score Details (7.0)
Base Score Metrics: - Exploitability Metrics: - Attack Vector: Local - Attack Complexity: High - Privileges Required: Low - User Interaction: None - Scope: Unchanged - Impact Metrics: - Confidentiality Impact: High - Integrity Impact: High - Availability Impact: High
For more information on CVSS3 Scores, click here.Suggested Fix
Type: Upgrade version
Origin: https://nvd.nist.gov/vuln/detail/CVE-2018-18955
Release Date: 2018-11-16
Fix Resolution: linux-yocto - 5.4.20+gitAUTOINC+c11911d4d1_f4d7dbafb1,4.8.26+gitAUTOINC+1c60e003c7_27efc3ba68
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