CVE intelligence and bounded remediation

CVE-2018-18397 — Linux Linux Kernel security vulnerability

Medium CVSS 5.5

The userfaultfd implementation in the Linux kernel before 4.19.7 mishandles access control for certain UFFDIO_ ioctl calls, as demonstrated by allowing local users to write data into holes in a tmpfs file (if the user has read-only access to that file, and that file contains holes), related to fs/userfaultfd.c and mm/userfaultfd.c.

Severity
Medium
CVSS
5.5 (3.0)
Published
2018-12-12
CISA KEV
Not currently listed
Ecosystem
linux/kernel
Weaknesses
CWE-863

Affected products

  • linux / linux_kernel
  • redhat / openshift_container_platform / 3.11
  • redhat / virtualization_host / 4.0
  • redhat / enterprise_linux_desktop / 7.0
  • redhat / enterprise_linux_server / 7.0
  • redhat / enterprise_linux_server_aus / 7.4

Showing 6 representative product identities from 17 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Authorization bypass, IDOR, and cross-tenant access

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Map object and action authorization checks across API, UI, batch, import/export, and background-job paths.
  • Identify tenant, ownership, role, and policy boundaries for affected resources and administrative operations.
  • Use synthetic fixtures to compare intended access matrices without accessing another user's real data.

Remediate safely

  • Enforce server-side authorization at each resource access and state transition using the authenticated principal and trusted tenant context.
  • Scope data queries by tenant and ownership; treat client-supplied identifiers, roles, and policy claims as untrusted.
  • Add deny-by-default policy tests for horizontal and vertical access across every affected transport.

Authoritative sources

Complete CVE record and remediation plan

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