High severity7.0NVD Advisory· Published Nov 16, 2018· Updated Jun 17, 2026
CVE-2018-18955
CVE-2018-18955
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
6- Range: >=4.15,<4.19.2
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*+ 2 more
- cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
- cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
- cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:*
Patches
Vulnerability mechanics
References
15- git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/nvdPatchVendor Advisory
- bugs.chromium.org/p/project-zero/issues/detailnvdPatchThird Party Advisory
- cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.18.19nvdPatchVendor Advisory
- cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.19.2nvdPatchVendor Advisory
- github.com/torvalds/linux/commit/d2f007dbe7e4c9583eea6eb04d60001e85c6f1bdnvdPatchVendor Advisory
- www.exploit-db.com/exploits/45886/nvdExploitPatchThird Party AdvisoryVDB Entry
- www.exploit-db.com/exploits/45915/nvdExploitThird Party AdvisoryVDB Entry
- www.securityfocus.com/bid/105941nvdThird Party AdvisoryVDB Entry
- usn.ubuntu.com/3832-1/nvdThird Party Advisory
- usn.ubuntu.com/3833-1/nvdThird Party Advisory
- usn.ubuntu.com/3835-1/nvdThird Party Advisory
- usn.ubuntu.com/3836-1/nvdThird Party Advisory
- usn.ubuntu.com/3836-2/nvdThird Party Advisory
- security.netapp.com/advisory/ntap-20190416-0003/nvd
- support.f5.com/csp/article/K39103040nvd
News mentions
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