Auth bypass in Linux Kernel
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.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.5 (Medium). Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.005 (41.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 41st percentile — 41.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Linux Kernel
- Canonical Ubuntu Linux — versions 14.04, 16.04, 18.04
- Red Hat Enterprise Linux Desktop — versions 7.0
- Red Hat Enterprise Linux Server — versions 7.0
- Red Hat Enterprise Linux Server Aus — versions 7.4, 7.6
- Red Hat Enterprise Linux Server Eus — versions 7.4, 7.5, 7.6
- Red Hat Enterprise Linux Server Tus — versions 7.4, 7.6
- Red Hat Enterprise Linux Workstation — versions 7.0
- Red Hat Openshift Container Platform — versions 3.11
- Red Hat Virtualization Host — versions 4.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- usn.ubuntu.com/3903-2/ (vendor-advisory, Third Party Advisory)
- cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.14.87 (Patch, Vendor Advisory)
- github.com/torvalds/linux/commit/29ec90660d68bbdd69507c1c8b4e33aa299278b1 (Patch, Third Party Advisory)
- usn.ubuntu.com/3901-2/ (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2019:0324 (vendor-advisory, Third Party Advisory)
- bugs.chromium.org/p/project-zero/issues/detail (Exploit, Third Party Advisory, Issue Tracking)
- access.redhat.com/errata/RHSA-2019:0202 (vendor-advisory, Third Party Advisory)
- access.redhat.com/errata/RHSA-2019:0163 (vendor-advisory, Third Party Advisory)
- git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/ (Patch, Third Party Advisory)
- cdn.kernel.org/pub/linux/kernel/v4.x/ChangeLog-4.19.7 (Patch, Vendor Advisory)
Frequently asked questions
- What is CVE-2018-18397?
- CVE-2018-18397 is a medium-severity vulnerability in Linux Kernel, classified under Incorrect Authorization. CVSS score: 5.5/10. Published 2018-12-12.
- How severe is CVE-2018-18397?
- Medium severity. CVSS v3 base score is 5.5 out of 10.
- Is CVE-2018-18397 known to be exploited?
- 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.