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SPECTRE(1) User Commands SPECTRE(1)


Spectre - Spectre & Meltdown vulnerability/mitigation checker


Spectre and Meltdown mitigation detection tool v0.44

spectre-meltdown-checker [options]
Live mode (manual): spectre-meltdown-checker [options] <[--kernel <kimage>] [--config <kconfig>] [--map <mapfile>]> --live Offline mode: spectre-meltdown-checker [options] <[--kernel <kimage>] [--config <kconfig>] [--map <mapfile>]>
Two modes are available.
First mode is the "live" mode (default), it does its best to find information about the currently running kernel. To run under this mode, just start the script without any option (you can also use --live explicitly)
Second mode is the "offline" mode, where you can inspect a non-running kernel. This mode is automatically enabled when you specify the location of the kernel file, config and files:
specify a (possibly compressed) Linux or BSD kernel file
specify a kernel config file (Linux only)
specify a kernel file (Linux only)
If you want to use live mode while specifying the location of the kernel, config or map file yourself, you can add --live to the above options, to tell the script to run in live mode instead of the offline mode, which is enabled by default when at least one file is specified on the command line.
don't use color codes
increase verbosity level, possibly several times
produce an additional human-readable explanation of actions to take to mitigate a vulnerability
require IBPB to deem Variant 2 as mitigated also require SMT disabled + unconditional L1D flush to deem Foreshadow-NG VMM as mitigated also require SMT disabled to deem MDS vulnerabilities mitigated
don't use the /sys interface even if present [Linux]
only use the /sys interface, don't run our own checks [Linux]
special mode for CoreOS (use an ephemeral toolbox to inspect kernel) [Linux]
specify a prefix for cross-inspecting a kernel of a different arch, for example "aarch64-linux-gnu-", so that invoked tools will be prefixed with this (i.e. aarch64-linux-gnu-objdump)
produce machine readable output, this is the default if --batch is specified alone
produce only one line with the vulnerabilities separated by spaces
produce JSON output formatted for Puppet, Ansible, Chef...
produce machine readable output formatted for NRPE
produce output for consumption by prometheus-node-exporter
specify which variant you'd like to check, by default all variants are checked VARIANT can be one of 1, 2, 3, 3a, 4, l1tf, msbds, mfbds, mlpds, mdsum, taa, mcepsc, srbds can be specified multiple times (e.g. --variant 2 --variant 3)
specify which CVE you'd like to check, by default all supported CVEs are checked
only check for CPU information, don't check for any variant
skip CPU information and checks, if you're inspecting a kernel not to be run on this host
override the detection of the presence of a hypervisor, default: auto
update our local copy of the CPU microcodes versions database (using the awesome MCExtractor project and the Intel firmwares GitHub repository)
same as --update-fwdb but update builtin DB inside the script itself
used to mimick a CPU on an other system, mainly used to help debugging this script
Return codes:
0 (not vulnerable), 2 (vulnerable), 3 (unknown), 255 (error)
IMPORTANT: A false sense of security is worse than no security at all. Please use the --disclaimer option to understand exactly what this script does.


The full documentation for Spectre is maintained as a Texinfo manual. If the info and Spectre programs are properly installed at your site, the command

info Spectre

should give you access to the complete manual.

October 2021 Spectre and Meltdown mitigation detection tool v0.44