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MEDIUM

CVE-2018-18397

CVSS v3

5.5

MEDIUM

EPSS Score

0.5 %

exploit probability, as of 2026-10-19

CISA KEV

No

known exploited

Exploitation

—

SSVC status

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Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Vendor advisories

  • CVE-2018-18397 Red Hat Product Security413 products fixed

    kernel: userfaultfd bypasses tmpfs file permissions

  • RHSA-2019:0831 Red Hat Product Security26 products fixed

    Red Hat Security Advisory: kernel-alt security and bug fix update

  • RHSA-2019:0324 Red Hat Product Security111 products fixed

    Red Hat Security Advisory: kernel security and bug fix update

  • RHSA-2019:0163 Red Hat Product Security165 products fixed

    Red Hat Security Advisory: kernel security, bug fix, and enhancement update

  • RHSA-2019:0202 Red Hat Product Security111 products fixed

    Red Hat Security Advisory: kernel security and bug fix update

Full record on NVD

Description

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.

Technical details

Published
2018-12-12

Frequently asked questions

What is CVE-2018-18397?

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.

Is CVE-2018-18397 actively exploited?

Active exploitation of CVE-2018-18397 has not been confirmed. Its EPSS score was 0.5% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2018-18397?

CVE-2018-18397 has a CVSS v3 base score of 5.5 (MEDIUM severity).

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