CVE-2024-43378: calamares-nixos-extensions LUKS keyfile exposure regression on legacy BIOS systems

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-08-16 · updated 2026-06-17
Weakness: CWE-256

Description

calamares-nixos-extensions provides Calamares branding and modules for NixOS, a distribution of GNU/Linux. Users who installed NixOS through the graphical installer who used manual disk partitioning to create a setup where the system was booted via legacy BIOS rather than UEFI; some disk partitions are encrypted; but the partitions containing either `/` or `/boot` are unencrypted; have their LUKS disk encryption key file in plain text either in `/crypto_keyfile.bin`, or in a CPIO archive attached to their NixOS initrd. `nixos-install` is not affected, nor are UEFI installations, nor was the default automatic partitioning configuration on legacy BIOS systems. The problem has been fixed in calamares-nixos-extensions 0.3.17, which was included in NixOS. The current installer images for the NixOS 24.05 and unstable (24.11) channels are unaffected. The fix reached 24.05 at 2024-08-13 20:06:59 UTC, and unstable at 2024-08-15 09:00:20 UTC. Installer images downloaded before those times may be vulnerable. The best solution for affected users is probably to back up their data and do a complete reinstallation. However, the mitigation procedure in GHSA-3rvf-24q2-24ww should work solely for the case where `/` is encrypted but `/boot` is not. If `/` is unencrypted, then the `/crypto_keyfile.bin` file will need to be deleted in addition to the remediation steps in the previous advisory. This issue is a partial regression of CVE-2023-36476 / GHSA-3rvf-24q2-24ww, which was more severe as it applied to the default configuration on BIOS systems.

Affected products

NixOS calamares-nixos-extensions: before 0.3.17 — fixed in 0.3.17

How to fix

Upgrade to a fixed version: NixOS calamares-nixos-extensions 0.3.17. Check the vendor advisory for mitigations.

References

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