Vulnerability Details : CVE-2018-18955

Public exploit exists!
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.
Published 2018-11-16 20:29:00
Updated 2020-08-24 17:37:01
Source MITRE
View at NVD,   CVE.org
Vulnerability category: Gain privilege

Products affected by CVE-2018-18955

Exploit prediction scoring system (EPSS) score for CVE-2018-18955

EPSS FAQ
0.11%
Probability of exploitation activity in the next 30 days EPSS Score History
~ 44 %
Percentile, the proportion of vulnerabilities that are scored at or less

Metasploit modules for CVE-2018-18955

  • Linux Nested User Namespace idmap Limit Local Privilege Escalation
    Disclosure Date: 2018-11-15
    First seen: 2020-04-26
    exploit/linux/local/nested_namespace_idmap_limit_priv_esc
    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

CVSS scores for CVE-2018-18955

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
4.4
 MEDIUM AV:L/AC:M/Au:N/C:P/I:P/A:P
3.4
6.4
 NIST
7.0
 HIGH CVSS:3.0/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
1.0
5.9
 NIST

CWE ids for CVE-2018-18955

  • The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. This allows attackers to bypass intended access restrictions.
    Assigned by: nvd@nist.gov (Primary)

References for CVE-2018-18955

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