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Fencer Vulns
medium 5.5

CVE-2018-18397 json

The userfaultfd implementation in the Linux kernel before 4.19.7 mishandles access control for certain UFFDIO_ ioctl calls, as demonstrated…

published 2018-12-12 7 y ago modified 2026-06-17 4 mo ago also EUVD-2018-10126

cvss
5.5
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 43%
public exploits
0
none known

Summary

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.

Patch / fix

  • linux linux_kernel 4.19.7
  • linux Debian 14, Debian 13, Debian 12 4.19.9-1

debian advisories DEBIAN-CVE-2018-18397

  • linux Ubuntu 18.04 LTS 4.15.0-46.49
  • linux-aws Ubuntu 18.04 LTS 4.15.0-1033.35
  • linux-gcp Ubuntu 16.04 LTS 4.15.0-1028.29~16.04.1
  • linux-gcp Ubuntu 18.04 LTS 4.15.0-1028.29
  • linux-hwe Ubuntu 16.04 LTS 4.15.0-46.49~16.04.1
  • linux-hwe Ubuntu 18.04 LTS 4.18.0-16.17~18.04.1
  • linux-kvm Ubuntu 18.04 LTS 4.15.0-1030.30
  • linux-oem Ubuntu 18.04 LTS 4.15.0-1034.39

ubuntu advisories UBUNTU-CVE-2018-18397

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • kernel-alt RHEL 7 4.14.0-115.7.1.el7a
  • perf RHEL 7 4.14.0-115.7.1.el7a
  • kernel RHEL 7 4.14.0-115.7.1.el7a
  • python-perf RHEL 7 4.14.0-115.7.1.el7a
  • kernel-tools RHEL 7 4.14.0-115.7.1.el7a
  • kernel-tools-libs RHEL 7 4.14.0-115.7.1.el7a
  • kernel-bootwrapper RHEL 7 4.14.0-115.7.1.el7a
  • kernel-abi-whitelists RHEL 7 4.14.0-115.7.1.el7a

red hat advisories RHSA-2019:0831RHSA-2019:0324RHSA-2019:0202RHSA-2019:0163

  • kernel-syms SLE Module for Development Tools 15 4.12.14-25.28.1
  • kernel-source SLE Module for Development Tools 15, SLE Module for Basesystem 15 4.12.14-25.28.1
  • kernel-default SLE Workstation Extension 15, SLE Module for Legacy 15, SLE Module for Basesystem 15 +2 more 4.12.14-25.28.1
  • kernel-vanilla SLE Module for Development Tools 15 4.12.14-25.28.1
  • kernel-zfcpdump SLE Module for Basesystem 15 4.12.14-25.28.1
  • kernel-obs-build SLE Module for Development Tools 15 4.12.14-25.28.1
  • kernel-azure SLES for SAP 12 SP4, SLES 12 SP4 4.12.14-6.6.2
  • kernel-syms-azure SLES for SAP 12 SP4, SLES 12 SP4 4.12.14-6.6.2

suse advisories SUSE-SU-2019:0224-1SUSE-SU-2019:0222-1SUSE-SU-2019:0196-1SUSE-SU-2019:0150-1

  • kernel-source openSUSE Leap 15.0 4.12.14-lp150.12.45.1

opensuse advisories openSUSE-SU-2019:0065-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2018-18397 updated cvss 6.1

kernel: userfaultfd bypasses tmpfs file permissions

  • Red Hat Enterprise Linux Client (v. 7) perf 3.10.0-957.5.1.el7, kernel 3.10.0-957.5.1.el7, bpftool 3.10.0-957.5.1.el7, python-perf 3.10.0-957.5.1.el7, kernel-tools 3.10.0-957.5.1.el7, kernel-tools-libs 3.10.0-957.5.1.el7, +2 more Red Hat Enterprise Linux Client Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-957.5.1.el7 Red Hat Enterprise Linux ComputeNode (v. 7) perf 3.10.0-957.5.1.el7, kernel 3.10.0-957.5.1.el7, bpftool 3.10.0-957.5.1.el7, python-perf 3.10.0-957.5.1.el7, kernel-tools 3.10.0-957.5.1.el7, kernel-tools-libs 3.10.0-957.5.1.el7, +2 more
    fixed: vendor fix RHSA-2019:0163
  • Red Hat Enterprise Linux ComputeNode EUS (v. 7.4) perf 3.10.0-693.44.1.el7, kernel 3.10.0-693.44.1.el7, python-perf 3.10.0-693.44.1.el7, kernel-tools 3.10.0-693.44.1.el7, kernel-tools-libs 3.10.0-693.44.1.el7, kernel-abi-whitelists 3.10.0-693.44.1.el7, +1 more
    fixed: vendor fix RHSA-2019:0324
  • Red Hat Enterprise Linux ComputeNode EUS (v. 7.5) perf 3.10.0-862.27.1.el7, kernel 3.10.0-862.27.1.el7, python-perf 3.10.0-862.27.1.el7, kernel-tools 3.10.0-862.27.1.el7, kernel-tools-libs 3.10.0-862.27.1.el7, kernel-abi-whitelists 3.10.0-862.27.1.el7, +1 more
    fixed: vendor fix RHSA-2019:0202
  • Red Hat Enterprise Linux ComputeNode Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-957.5.1.el7
    fixed: vendor fix RHSA-2019:0163
  • Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.4) kernel-debuginfo-common-x86_64 3.10.0-693.44.1.el7
    fixed: vendor fix RHSA-2019:0324
  • Red Hat Enterprise Linux ComputeNode Optional EUS (v. 7.5) kernel-debuginfo-common-x86_64 3.10.0-862.27.1.el7
    fixed: vendor fix RHSA-2019:0202
  • Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server (v. 7) perf 4.14.0-115.7.1.el7a, kernel 4.14.0-115.7.1.el7a, kernel-alt 4.14.0-115.7.1.el7a, python-perf 4.14.0-115.7.1.el7a, kernel-tools 4.14.0-115.7.1.el7a, kernel-tools-libs 4.14.0-115.7.1.el7a, +3 more Red Hat Enterprise Linux for ARM and IBM Power LE (POWER9) Server Optional (v. 7) kernel-debuginfo-common-ppc64le 4.14.0-115.7.1.el7a
    fixed: vendor fix RHSA-2019:0831
  • Red Hat Enterprise Linux Server (v. 7) perf 3.10.0-957.5.1.el7, kernel 3.10.0-957.5.1.el7, bpftool 3.10.0-957.5.1.el7, python-perf 3.10.0-957.5.1.el7, kernel-kdump 3.10.0-957.5.1.el7, kernel-tools 3.10.0-957.5.1.el7, +7 more
    fixed: vendor fix RHSA-2019:0163
show 7 more
  • Red Hat Enterprise Linux Server EUS (v. 7.4) perf 3.10.0-693.44.1.el7, kernel 3.10.0-693.44.1.el7, python-perf 3.10.0-693.44.1.el7, kernel-kdump 3.10.0-693.44.1.el7, kernel-tools 3.10.0-693.44.1.el7, kernel-tools-libs 3.10.0-693.44.1.el7, +6 more
    fixed: vendor fix RHSA-2019:0324
  • Red Hat Enterprise Linux Server EUS (v. 7.5) perf 3.10.0-862.27.1.el7, kernel 3.10.0-862.27.1.el7, python-perf 3.10.0-862.27.1.el7, kernel-kdump 3.10.0-862.27.1.el7, kernel-tools 3.10.0-862.27.1.el7, kernel-tools-libs 3.10.0-862.27.1.el7, +6 more
    fixed: vendor fix RHSA-2019:0202
  • Red Hat Enterprise Linux Server Optional (v. 7) kernel-debuginfo-common-ppc64 3.10.0-957.5.1.el7, kernel-debuginfo-common-x86_64 3.10.0-957.5.1.el7, kernel-debuginfo-common-ppc64le 3.10.0-957.5.1.el7
    fixed: vendor fix RHSA-2019:0163
  • Red Hat Enterprise Linux Server Optional EUS (v. 7.4) kernel-debuginfo-common-ppc64 3.10.0-693.44.1.el7, kernel-debuginfo-common-x86_64 3.10.0-693.44.1.el7, kernel-debuginfo-common-ppc64le 3.10.0-693.44.1.el7
    fixed: vendor fix RHSA-2019:0324
  • Red Hat Enterprise Linux Server Optional EUS (v. 7.5) kernel-debuginfo-common-ppc64 3.10.0-862.27.1.el7, kernel-debuginfo-common-x86_64 3.10.0-862.27.1.el7, kernel-debuginfo-common-ppc64le 3.10.0-862.27.1.el7
    fixed: vendor fix RHSA-2019:0202
  • Red Hat Enterprise Linux Workstation (v. 7) perf 3.10.0-957.5.1.el7, kernel 3.10.0-957.5.1.el7, bpftool 3.10.0-957.5.1.el7, python-perf 3.10.0-957.5.1.el7, kernel-tools 3.10.0-957.5.1.el7, kernel-tools-libs 3.10.0-957.5.1.el7, +2 more Red Hat Enterprise Linux Workstation Optional (v. 7) kernel-debuginfo-common-x86_64 3.10.0-957.5.1.el7
    fixed: vendor fix RHSA-2019:0163
  • Red Hat Enterprise Linux 5 kernel Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 more Red Hat Enterprise Linux 7 kernel-rt, kernel-rt-kvm, kernel-rt-trace, kernel-rt-debug-kvm, kernel-rt-trace-kvm Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise MRG 2 kernel-rt, mrg-rt-release, kernel-rt-trace, kernel-rt-vanilla, kernel-rt-firmware
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

0.51% chance of exploitation in the next 30 days, higher than 43% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • bugs.chromium.org https://bugs.chromium.org/p/project-zero/issues/detail?id=1700 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.0 5.5 CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
NVD 2.0 2.1 AV:L/AC:L/Au:N/C:N/I:P/A:N

Classification

Weakness
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.