What’s Vulnerable › Vulnerabilities

CVE-2018-18281

• Severity: high (CVSS 7.8 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2018-10-30 · updated 2026-06-17
• Weakness: CWE-459

Description

Since Linux kernel version 3.2, the mremap() syscall performs TLB flushes after dropping pagetable locks. If a syscall such as ftruncate() removes entries from the pagetables of a task that is in the middle of mremap(), a stale TLB entry can remain for a short time that permits access to a physical page after it has been released back to the page allocator and reused. This is fixed in the following kernel versions: 4.9.135, 4.14.78, 4.18.16, 4.19.

Affected products

• Canonical Ubuntu Linux: 12.04, 14.04, 16.04, 18.04, 18.10
• Debian Linux: 8.0
• Linux kernel: from 3.2 before 4.9.135; from 4.9.136 before 4.14.78; from 4.14.79 before 4.18.16; from 4.18.17 before 4.19 — fixed in 4.14.78, 4.18.16, 4.19, 4.9.135

How to fix

Upgrade to a fixed version: Linux kernel 4.14.78, 4.18.16, 4.19, 4.9.135. Check the vendor advisory for mitigations.

References

• http://packetstormsecurity.com/files/150001/Linux-mremap-TLB-Flush-Too-Late.html
• http://www.openwall.com/lists/oss-security/2018/10/29/5
• http://www.securityfocus.com/bid/105761
• http://www.securityfocus.com/bid/106503
• https://access.redhat.com/errata/RHSA-2019:0831
• https://access.redhat.com/errata/RHSA-2019:2029
• https://access.redhat.com/errata/RHSA-2019:2043
• https://access.redhat.com/errata/RHSA-2020:0036
• https://access.redhat.com/errata/RHSA-2020:0100
• https://access.redhat.com/errata/RHSA-2020:0103
• https://access.redhat.com/errata/RHSA-2020:0179
• https://bugs.chromium.org/p/project-zero/issues/detail?id=1695

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