coreos-installer improperly verifies GPG signature when decompressing gzipped artifact

Exploitation

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

CVSS

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

EPSS

• CVE-2021-20319: 0.52% estimated exploitation activity in the next 30 days; percentile 44.15 (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 coreos-installer fails to correctly verify GPG signatures when decompressing gzip-compressed artifacts. This allows bypass of signature verification in cases where coreos-installer decompresses a downloaded OS image, allowing an attacker who can modify the OS image to compromise a newly-installed system. Default installations from ISO or PXE media in Fedora CoreOS, RHEL CoreOS, and RHEL for Edge are not affected, as coreos-installer installs from an OS image shipped as part of the install media. These flows are affected: 1. Installing with --image-file, --image-url, or coreos.inst.imageurl. For example, if a user has a local mirror of installation images, an attacker could replace an image with a gzip-compressed alternative (even if the file extension is .xz). The result: Notice that GPG reports a bad signature, but coreos-installer continues anyway. Automation that relies on coreos-installer's exit status will not notice either. 2. coreos-installer download --decompress…

Published by the source

12 Oct 2021, 16:06 UTC

Last modified by the source

22 Dec 2025, 16:27 UTC

Source last checked

26 Oct 2026, 15:39 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-3r3g-g73x-g593

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# Patch Next advisory brief: CVE-2021-20319

Advisory: coreos-installer improperly verifies GPG signature when decompressing gzipped artifact
IDs: CVE-2021-20319, GHSA-3r3g-g73x-g593
Record: https://patchnext.com/advisories/cve-2021-20319 (revision 1, source checked 26 Oct 2026, 15:39 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.8)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: coreos-installer 0.10.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- crates.io coreos-installer: affected < 0.10.1; fixed in 0.10.1

## 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-3r3g-g73x-g593 (GitHub-reviewed advisory GHSA-3r3g-g73x-g593 lists affected ranges: crates.io coreos-installer >=0 <0.10.1)

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