How severe is CVE-2021-3917?

CVE-2021-3917 has a CVSS score of 5.5/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2021-3917?

CVE-2021-3917 affects the following packages: coreos-installer (crates.io). Ecosystems affected: crates.io.

How do I fix CVE-2021-3917?

Update coreos-installer to 0.10.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3917 is resolved across your whole dependency graph.

How do I detect CVE-2021-3917 in my crates.io dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for coreos-installer, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-3917 if there is no patch (or I can't update yet)?

Close the privilege gap rather than the entry point: audit which accounts, roles and service identities can reach the affected operation, drop the component to the least privilege it actually needs, and review file and directory permissions created by earlier installs — a default left in place is what makes this reachable.

Is CVE-2021-3917 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-3917 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-3917?

CVE-2021-3917 has an EPSS (Exploit Prediction Scoring System) score of 0.2%, placing it in the 13th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-3917?

CVE-2021-3917 is classified as Incorrect Default Permissions (CWE-276). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-3917 published, and has it been updated?

CVE-2021-3917 was published on August 23, 2022 and was last updated on July 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🦀

🦀 crates.io

Not in CISA KEV

MEDIUM severity

CVE-2021-3917 — coreos-installer

MEDIUMFix: coreos/coreos-installer@2a36405

CVE-2021-3917 is a medium-severity (CVSS 5.5) Incorrect Default Permissions vulnerability in coreos-installer. A fix is available for coreos-installer — see the affected versions and patch details below.

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

Also known asGHSA-862g-9h5m-m3qv

Published

Aug 23, 2022

Updated

Jul 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 12, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

0.2%probability of exploitation in next 30 days

Lower Risk+0.00%

Lower risk than most CVEs13th percentile — riskier than 13% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-3917 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

🦀coreos-installer

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.

Description

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 is required.

On other systems, /boot/ignition/config.ign can be removed manually, as it is not used after provisioning is complete:

sudo mount -o remount,rw /boot
sudo rm -rf /boot/ignition

References

For more information, see https://github.com/coreos/fedora-coreos-tracker/issues/889.

For more information

If you have any questions or comments about this advisory, open an issue in coreos-installer or email the CoreOS development mailing list.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`coreos-installer`	all versions	0.10.0`cargo update -p coreos-installer --precise 0.10.0`

Affected Products

1 product · 1 configurations

Application

coreos-installerredhat

< 0.10.0

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for coreos-installer, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update coreos-installer to 0.10.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3917 is resolved across your whole dependency graph.
Workarounds
Close the privilege gap rather than the entry point: audit which accounts, roles and service identities can reach the affected operation, drop the component to the least privilege it actually needs, and review file and directory permissions created by earlier installs — a default left in place is what makes this reachable.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Product	Fixed in	Advisory
Red Hat OpenShift Container Platform 4.8	`coreos-installer-0:0.9.0-8.rhaos4.8.el8`	RHSA-2021:4829
Red Hat OpenShift Container Platform 4.9	`coreos-installer-0:0.10.0-2.rhaos4.9.el8`	RHSA-2021:3758

Frequently Asked Questions

### 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](https://g