CVE-2018-18955

moderate-risk
Published 2018-11-16

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.

Do I need to act?

~
9.6% chance of exploitation in next 30 days
EPSS score — moderate exploit probability
-
Not on CISA KEV list
No confirmed active exploitation reported to CISA
!
6 public exploits available
45886, 45915, 47164 and 3 more
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
7
CVSS 7.0/10 High
LOCAL / HIGH complexity

Affected Products (4)

Affected Vendors

Linux Canonical

References (30)

Patch http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d2f007...
Third Party Advisory http://www.securityfocus.com/bid/105941
Patch https://bugs.chromium.org/p/project-zero/issues/detail?id=1712
Patch https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.18.19
Patch https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.19.2
Patch https://github.com/torvalds/linux/commit/d2f007dbe7e4c9583eea6eb04d60001e85c6f1b...
https://security.netapp.com/advisory/ntap-20190416-0003/
https://support.f5.com/csp/article/K39103040
Third Party Advisory https://usn.ubuntu.com/3832-1/
Third Party Advisory https://usn.ubuntu.com/3833-1/
Third Party Advisory https://usn.ubuntu.com/3835-1/
Third Party Advisory https://usn.ubuntu.com/3836-1/
Third Party Advisory https://usn.ubuntu.com/3836-2/
Exploit https://www.exploit-db.com/exploits/45886/
Exploit https://www.exploit-db.com/exploits/45915/
Patch http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=d2f007...
Third Party Advisory http://www.securityfocus.com/bid/105941
Patch https://bugs.chromium.org/p/project-zero/issues/detail?id=1712
Patch https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.18.19
Patch https://cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.19.2
and 10 more references
46
/ 100
moderate-risk
Severity 18/34 · Moderate
Exploitability 18/34 · Moderate
Exposure 10/34 · Low