Buildah processes using chroot isolation may leak environment values to intermediate processes

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-2021-3602: 0.33% estimated exploitation activity in the next 30 days; percentile 25.83 (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 When running processes using "chroot" isolation, the process being run can examine the environment variables of its immediate parent and grandparent processes (CVE-2021-3602). This isolation type is often used when running buildah in unprivileged containers, and it is often used to do so in CI/CD environments. If sensitive information is exposed to the original buildah process through its environment, that information will unintentionally be shared with child processes which it starts as part of handling RUN instructions or during buildah run. The commands that buildah is instructed to run can read that information if they choose to. Patches Users should upgrade packages, or images which contain packages, to include version 1.21.3 or later. Workarounds As a workaround, invoking buildah in a container under env -i to have it started with a reinitialized environment should prevent the leakage. For more information If you have any questions or comments about this advisory: Open…

Published by the source

19 Jul 2021, 15:19 UTC

Last modified by the source

29 Aug 2023, 18:32 UTC

Source last checked

26 Oct 2026, 14:58 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-7638-r9r3-rmjj

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# Patch Next advisory brief: CVE-2021-3602

Advisory: Buildah processes using chroot isolation may leak environment values to intermediate processes
IDs: CVE-2021-3602, GHSA-7638-r9r3-rmjj
Record: https://patchnext.com/advisories/cve-2021-3602 (revision 1, source checked 26 Oct 2026, 14:58 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: github.com/containers/buildah 1.21.3, 1.19.9, 1.17.2, 1.16.8. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/containers/buildah: affected <= 1.16.7; >= 1.17.0, <= 1.17.1; >= 1.18.0, <= 1.19.8; >= 1.20.0, <= 1.21.2; fixed in 1.21.3, 1.19.9, 1.16.8, 1.17.2

## Suggested inspection (read-only)
- Go github.com/containers/buildah: 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 github.com/containers/buildah.
- 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-7638-r9r3-rmjj (GitHub-reviewed advisory GHSA-7638-r9r3-rmjj lists affected ranges: Go github.com/containers/buildah >=0 =1.17.0 =1.18.0 =1.20.0 <=1.21.2)

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