coreos-installer < 0.10.0 writes world-readable Ignition config to installed system

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.5 · CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N

EPSS

• CVE-2021-3917: 0.24% estimated exploitation activity in the next 30 days; percentile 14.59 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Impact On systems installed with coreos-installer before 0.10.0, the user-provided Ignition config was written to /boot/ignition/config.ign with world-readable permissions, granting unprivileged users access to any secrets included in the config. Default configurations of Fedora CoreOS and RHEL CoreOS do not include any unprivileged user accounts. In addition, instances launched from a cloud image, and systems provisioned with the ignition.config.url kernel argument, do not use the config.ign file and are unaffected. Patches coreos-installer 0.10.0 and later writes the Ignition config with restricted permissions. Workarounds On Fedora CoreOS systems installed from version 34.20210711.3.0 (stable), 34.20210711.2.0 (testing), 34.20210711.1.1 (next) and later, the /boot/ignition directory and its contents are removed after provisioning is complete. All Fedora CoreOS systems that have updated to these versions or later have automatically removed the /boot/ignition directory and no action…

Published by the source

8 Nov 2021, 18:01 UTC

Last modified by the source

29 Jan 2023, 05:01 UTC

Source last checked

26 Oct 2026, 15:33 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-862g-9h5m-m3qv

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# Patch Next advisory brief: CVE-2021-3917

Advisory: coreos-installer < 0.10.0 writes world-readable Ignition config to installed system
IDs: CVE-2021-3917, GHSA-862g-9h5m-m3qv
Record: https://patchnext.com/advisories/cve-2021-3917 (revision 1, source checked 26 Oct 2026, 15:33 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: coreos-installer 0.10.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io coreos-installer: affected < 0.10.0; fixed in 0.10.0

## Suggested inspection (read-only)
- crates.io coreos-installer: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on coreos-installer.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-862g-9h5m-m3qv (GitHub-reviewed advisory GHSA-862g-9h5m-m3qv lists affected ranges: crates.io coreos-installer >=0 <0.10.0)

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