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spectre-meltdown-checker - Man Page

Spectre and Meltdown mitigation detection tool

Examples (TL;DR)


Spectre and Meltdown mitigation detection tool v0.46


Live mode (auto):

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 System.map files:

--kernel kernel_file

specify a (possibly compressed) Linux or BSD kernel file

--config kernel_config

specify a kernel config file (Linux only)

--map kernel_map_file

specify a kernel System.map 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

--verbose,  -v

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]

--arch-prefix PREFIX

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)

--batch text

produce machine readable output, this is the default if --batch is specified alone

--batch short

produce only one line with the vulnerabilities separated by spaces

--batch json

produce JSON output formatted for Puppet, Ansible, Chef...

--batch nrpe

produce machine readable output formatted for NRPE

--batch prometheus

produce output for consumption by prometheus-node-exporter

--variant VARIANT

specify which variant you'd like to check, by default all variants are checked. can be used multiple times (e.g. --variant 3a --variant l1tf) for a list of supported VARIANT parameters, use --variant help

--cve CVE

specify which CVE you'd like to check, by default all supported CVEs are checked can be used multiple times (e.g. --cve CVE-2017-5753 --cve CVE-2020-0543)


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

--vmm [auto,yes,no]

override the detection of the presence of a hypervisor, default: auto


allow probing for write-only MSRs, this might produce kernel logs or be blocked by your system

--cpu [#,all]

interact with CPUID and MSR of CPU core number #, or all (default: CPU core 0)


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.


January 2024 Spectre and Meltdown mitigation detection tool v0.46