CVE-2018-8897: Apple Mac OS X

High severity, CVSS 7.8. EPSS: 18.5% chance of exploitation in the next 30 days.

A statement in the System Programming Guide of the Intel 64 and IA-32 Architectures Software Developer's Manual (SDM) was mishandled in the development of some or all operating-system kernels, resulting in unexpected behavior for #DB exceptions that are deferred by MOV SS or POP SS, as demonstrated by (for example) privilege escalation in Windows, macOS, some Xen configurations, or FreeBSD, or a Linux kernel crash. The MOV to SS and POP SS instructions inhibit interrupts (including NMIs), data breakpoints, and single step trap exceptions until the instruction boundary following the next instruction (SDM Vol. 3A; section 6.8.3). (The inhibited data breakpoints are those on memory accessed by the MOV to SS or POP to SS instruction itself.) Note that debug exceptions are not inhibited by the interrupt enable (EFLAGS.IF) system flag (SDM Vol. 3A; section 2.3). If the instruction following the MOV to SS or POP to SS instruction is an instruction like SYSCALL, SYSENTER, INT 3, etc. that transfers control to the operating system at CPL < 3, the debug exception is delivered after the transfer to CPL < 3 is complete. OS kernels may not expect this order of events and may therefore experience unexpected behavior when it occurs.

Affected products

  • Apple Mac OS X: before 10.13.4 (fixed in 10.13.4)
  • Canonical Ubuntu Linux: version 14.04 only; version 16.04 only; version 17.10 only
  • Citrix Xenserver: version 6.0.2 only; version 6.2.0 only; version 6.5 only; version 7.0 only; version 7.1 only; version 7.2 only; …
  • Debian Debian Linux: version 7.0 only; version 8.0 only; version 9.0 only
  • Freebsd Freebsd: from 11.0, before 11.1 (fixed in 11.1)
  • Red Hat Enterprise Linux Server: version 7.0 only
  • Red Hat Enterprise Linux Workstation: version 7.0 only
  • Red Hat Enterprise Virtualization Manager: version 3.0 only
  • Synology Diskstation Manager: version 5.2 only; version 6.0 only; version 6.1 only
  • Synology Skynas: affected versions not specified
  • Xen Xen: affected versions not specified

Published 2018-05-08. Last modified 2026-06-17.