Strix
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CVE-2018-18955

UnknownEPSS 7.61%

Last modified

CVE-2018-18955 is a vulnerability of currently unknown severity. 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. EPSS estimates a 7.61% chance of exploitation in the next 30 days.

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.

Metrics

EPSS Probability
7.61%

93.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
LinuxLinux Kernel>= 4.15, < 4.19.2
CanonicalUbuntu Linux16.04
CanonicalUbuntu Linux18.04
CanonicalUbuntu Linux18.10

References

Timeline

Published
Last Modified
Status
Modified

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.
How severe is CVE-2018-18955?
Severity scoring for CVE-2018-18955 is pending analysis. The EPSS model estimates a 7.61% probability of exploitation in the next 30 days.
How do I fix CVE-2018-18955?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2018-18955?

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Source: NVD / NIST