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Vulnerability Details : 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.
Publish Date : 2018-11-16 Last Update Date : 2019-04-16
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- CVSS Scores & Vulnerability Types

CVSS Score
4.4
Confidentiality Impact Partial (There is considerable informational disclosure.)
Integrity Impact Partial (Modification of some system files or information is possible, but the attacker does not have control over what can be modified, or the scope of what the attacker can affect is limited.)
Availability Impact Partial (There is reduced performance or interruptions in resource availability.)
Access Complexity Medium (The access conditions are somewhat specialized. Some preconditions must be satistified to exploit)
Authentication Not required (Authentication is not required to exploit the vulnerability.)
Gained Access None
Vulnerability Type(s) Bypass a restriction or similar
CWE ID 20

- Products Affected By CVE-2018-18955

# Product Type Vendor Product Version Update Edition Language
1 OS Canonical Ubuntu Linux 16.04 ~~lts~~~ Version Details Vulnerabilities
2 OS Canonical Ubuntu Linux 18.04 ~~lts~~~ Version Details Vulnerabilities
3 OS Canonical Ubuntu Linux 18.10 Version Details Vulnerabilities
4 OS Linux Linux Kernel 4.15 RC3 Version Details Vulnerabilities
5 OS Linux Linux Kernel 4.15 RC4 Version Details Vulnerabilities
6 OS Linux Linux Kernel 4.15 RC5 Version Details Vulnerabilities
7 OS Linux Linux Kernel 4.15 Version Details Vulnerabilities
8 OS Linux Linux Kernel 4.15 RC6 Version Details Vulnerabilities
9 OS Linux Linux Kernel 4.15 RC1 Version Details Vulnerabilities
10 OS Linux Linux Kernel 4.15 RC7 Version Details Vulnerabilities
11 OS Linux Linux Kernel 4.15 RC2 Version Details Vulnerabilities
12 OS Linux Linux Kernel 4.15.1 Version Details Vulnerabilities
13 OS Linux Linux Kernel 4.15.2 Version Details Vulnerabilities
14 OS Linux Linux Kernel 4.15.3 Version Details Vulnerabilities
15 OS Linux Linux Kernel 4.15.4 Version Details Vulnerabilities
16 OS Linux Linux Kernel 4.15.5 Version Details Vulnerabilities
17 OS Linux Linux Kernel 4.15.6 Version Details Vulnerabilities
18 OS Linux Linux Kernel 4.15.7 Version Details Vulnerabilities
19 OS Linux Linux Kernel 4.15.8 Version Details Vulnerabilities
20 OS Linux Linux Kernel 4.15.9 Version Details Vulnerabilities
21 OS Linux Linux Kernel 4.15.10 Version Details Vulnerabilities
22 OS Linux Linux Kernel 4.15.11 Version Details Vulnerabilities
23 OS Linux Linux Kernel 4.15.12 Version Details Vulnerabilities
24 OS Linux Linux Kernel 4.15.13 Version Details Vulnerabilities
25 OS Linux Linux Kernel 4.15.14 Version Details Vulnerabilities
26 OS Linux Linux Kernel 4.15.15 Version Details Vulnerabilities
27 OS Linux Linux Kernel 4.15.16 Version Details Vulnerabilities
28 OS Linux Linux Kernel 4.15.17 Version Details Vulnerabilities
29 OS Linux Linux Kernel 4.15.18 Version Details Vulnerabilities
30 OS Linux Linux Kernel 4.16 RC3 Version Details Vulnerabilities
31 OS Linux Linux Kernel 4.16 RC4 Version Details Vulnerabilities
32 OS Linux Linux Kernel 4.16 Version Details Vulnerabilities
33 OS Linux Linux Kernel 4.16 RC5 Version Details Vulnerabilities
34 OS Linux Linux Kernel 4.16 RC Version Details Vulnerabilities
35 OS Linux Linux Kernel 4.16 RC6 Version Details Vulnerabilities
36 OS Linux Linux Kernel 4.16 RC1 Version Details Vulnerabilities
37 OS Linux Linux Kernel 4.16 RC7 Version Details Vulnerabilities
38 OS Linux Linux Kernel 4.16 RC2 Version Details Vulnerabilities
39 OS Linux Linux Kernel 4.16.1 Version Details Vulnerabilities
40 OS Linux Linux Kernel 4.16.2 Version Details Vulnerabilities
41 OS Linux Linux Kernel 4.16.3 Version Details Vulnerabilities
42 OS Linux Linux Kernel 4.16.4 Version Details Vulnerabilities
43 OS Linux Linux Kernel 4.16.5 Version Details Vulnerabilities
44 OS Linux Linux Kernel 4.16.6 Version Details Vulnerabilities
45 OS Linux Linux Kernel 4.16.7 Version Details Vulnerabilities
46 OS Linux Linux Kernel 4.16.8 Version Details Vulnerabilities
47 OS Linux Linux Kernel 4.16.9 Version Details Vulnerabilities
48 OS Linux Linux Kernel 4.16.10 Version Details Vulnerabilities
49 OS Linux Linux Kernel 4.16.11 Version Details Vulnerabilities
50 OS Linux Linux Kernel 4.16.12 Version Details Vulnerabilities
51 OS Linux Linux Kernel 4.16.13 Version Details Vulnerabilities
52 OS Linux Linux Kernel 4.16.14 Version Details Vulnerabilities
53 OS Linux Linux Kernel 4.16.15 Version Details Vulnerabilities
54 OS Linux Linux Kernel 4.16.16 Version Details Vulnerabilities
55 OS Linux Linux Kernel 4.16.17 Version Details Vulnerabilities
56 OS Linux Linux Kernel 4.16.18 Version Details Vulnerabilities
57 OS Linux Linux Kernel 4.17 RC4 Version Details Vulnerabilities
58 OS Linux Linux Kernel 4.17 RC5 Version Details Vulnerabilities
59 OS Linux Linux Kernel 4.17 Version Details Vulnerabilities
60 OS Linux Linux Kernel 4.17 RC6 Version Details Vulnerabilities
61 OS Linux Linux Kernel 4.17 RC1 Version Details Vulnerabilities
62 OS Linux Linux Kernel 4.17 RC7 Version Details Vulnerabilities
63 OS Linux Linux Kernel 4.17 RC2 Version Details Vulnerabilities
64 OS Linux Linux Kernel 4.17 RC3 Version Details Vulnerabilities
65 OS Linux Linux Kernel 4.17.1 Version Details Vulnerabilities
66 OS Linux Linux Kernel 4.17.2 Version Details Vulnerabilities
67 OS Linux Linux Kernel 4.17.3 Version Details Vulnerabilities
68 OS Linux Linux Kernel 4.17.4 Version Details Vulnerabilities
69 OS Linux Linux Kernel 4.17.5 Version Details Vulnerabilities
70 OS Linux Linux Kernel 4.17.6 Version Details Vulnerabilities
71 OS Linux Linux Kernel 4.17.7 Version Details Vulnerabilities
72 OS Linux Linux Kernel 4.17.8 Version Details Vulnerabilities
73 OS Linux Linux Kernel 4.17.9 Version Details Vulnerabilities
74 OS Linux Linux Kernel 4.18 RC8 Version Details Vulnerabilities
75 OS Linux Linux Kernel 4.18 RC3 Version Details Vulnerabilities
76 OS Linux Linux Kernel 4.18 RC4 Version Details Vulnerabilities
77 OS Linux Linux Kernel 4.18 RC5 Version Details Vulnerabilities
78 OS Linux Linux Kernel 4.18 Version Details Vulnerabilities
79 OS Linux Linux Kernel 4.18 RC6 Version Details Vulnerabilities
80 OS Linux Linux Kernel 4.18 RC1 Version Details Vulnerabilities
81 OS Linux Linux Kernel 4.18 RC7 Version Details Vulnerabilities
82 OS Linux Linux Kernel 4.18 RC2 Version Details Vulnerabilities
83 OS Linux Linux Kernel 4.18.1 Version Details Vulnerabilities
84 OS Linux Linux Kernel 4.18.2 Version Details Vulnerabilities
85 OS Linux Linux Kernel 4.18.3 Version Details Vulnerabilities
86 OS Linux Linux Kernel 4.18.4 Version Details Vulnerabilities
87 OS Linux Linux Kernel 4.18.5 Version Details Vulnerabilities
88 OS Linux Linux Kernel 4.18.6 Version Details Vulnerabilities
89 OS Linux Linux Kernel 4.18.7 Version Details Vulnerabilities
90 OS Linux Linux Kernel 4.18.8 Version Details Vulnerabilities
91 OS Linux Linux Kernel 4.18.9 Version Details Vulnerabilities
92 OS Linux Linux Kernel 4.18.10 Version Details Vulnerabilities
93 OS Linux Linux Kernel 4.18.11 Version Details Vulnerabilities
94 OS Linux Linux Kernel 4.18.12 Version Details Vulnerabilities
95 OS Linux Linux Kernel 4.18.13 Version Details Vulnerabilities
96 OS Linux Linux Kernel 4.18.14 Version Details Vulnerabilities
97 OS Linux Linux Kernel 4.18.15 Version Details Vulnerabilities
98 OS Linux Linux Kernel 4.18.16 Version Details Vulnerabilities
99 OS Linux Linux Kernel 4.18.19 Version Details Vulnerabilities
100 OS Linux Linux Kernel 4.19 RC2 Version Details Vulnerabilities
101 OS Linux Linux Kernel 4.19 RC8 Version Details Vulnerabilities
102 OS Linux Linux Kernel 4.19 RC3 Version Details Vulnerabilities
103 OS Linux Linux Kernel 4.19 RC4 Version Details Vulnerabilities
104 OS Linux Linux Kernel 4.19 RC5 Version Details Vulnerabilities
105 OS Linux Linux Kernel 4.19 Version Details Vulnerabilities
106 OS Linux Linux Kernel 4.19 RC6 Version Details Vulnerabilities
107 OS Linux Linux Kernel 4.19 RC1 Version Details Vulnerabilities
108 OS Linux Linux Kernel 4.19 RC7 Version Details Vulnerabilities
109 OS Linux Linux Kernel 4.19.1 Version Details Vulnerabilities

- Number Of Affected Versions By Product

Vendor Product Vulnerable Versions
Canonical Ubuntu Linux 3
Linux Linux Kernel 106

- References For CVE-2018-18955

https://www.exploit-db.com/exploits/45915/
EXPLOIT-DB 45915
http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d2f007dbe7e4c9583eea6eb04d60001e85c6f1bd
https://usn.ubuntu.com/3836-2/
UBUNTU USN-3836-2
https://github.com/torvalds/linux/commit/d2f007dbe7e4c9583eea6eb04d60001e85c6f1bd
http://www.securityfocus.com/bid/105941
BID 105941 Linux Kernel CVE-2018-18955 Local Privilege Escalation Vulnerability Release Date:2018-11-16
https://www.exploit-db.com/exploits/45886/
EXPLOIT-DB 45886
https://usn.ubuntu.com/3835-1/
UBUNTU USN-3835-1
https://usn.ubuntu.com/3833-1/
UBUNTU USN-3833-1
https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.19.2
https://usn.ubuntu.com/3832-1/
UBUNTU USN-3832-1
https://support.f5.com/csp/article/K39103040 CONFIRM
https://bugs.chromium.org/p/project-zero/issues/detail?id=1712
https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.18.19
https://usn.ubuntu.com/3836-1/
UBUNTU USN-3836-1
https://security.netapp.com/advisory/ntap-20190416-0003/ CONFIRM

- Metasploit Modules Related To CVE-2018-18955

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).
Module type : exploit Rank : great Platforms : Linux


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