opencontainers runc contains procfs race condition with a shared volume mount

Exploitation

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

CVSS

5.0 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:U/RC:U

EPSS

• CVE-2019-19921: 0.43% estimated exploitation activity in the next 30 days; percentile 37.65 (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 By crafting a malicious root filesystem (with /proc being a symlink to a directory which was inside a volume shared with another running container), an attacker in control of both containers can trick runc into not correctly configuring the container's security labels and not correctly masking paths inside /proc which contain potentially-sensitive information about the host (or even allow for direct attacks against the host). In order to exploit this bug, an untrusted user must be able to spawn custom containers with custom mount configurations (such that a volume is shared between two containers). It should be noted that we consider this to be a fairly high level of access for an untrusted user -- and we do not recommend allowing completely untrusted users to have such degrees of access without further restrictions. Specific Go Package Affected github.com/opencontainers/runc/libcontainer Patches This vulnerability has been fixed in 1.0.0-rc10. It should be noted that the…

Published by the source

27 May 2021, 18:41 UTC

Last modified by the source

8 Oct 2026, 11:04 UTC

Source last checked

26 Oct 2026, 15:29 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-fh74-hm69-rqjw

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# Patch Next advisory brief: CVE-2019-19921

Advisory: opencontainers runc contains procfs race condition with a shared volume mount
IDs: CVE-2019-19921, GHSA-fh74-hm69-rqjw
Record: https://patchnext.com/advisories/cve-2019-19921 (revision 1, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.0)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/opencontainers/runc 1.0.0-rc9.0.20200122160610-2fc03cc11c77. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/opencontainers/runc: affected < 1.0.0-rc9.0.20200122160610-2fc03cc11c77; fixed in 1.0.0-rc9.0.20200122160610-2fc03cc11c77

## Suggested inspection (read-only)
- Go github.com/opencontainers/runc: 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/opencontainers/runc.
- 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-fh74-hm69-rqjw (GitHub-reviewed advisory GHSA-fh74-hm69-rqjw lists affected ranges: Go github.com/opencontainers/runc >=0 <1.0.0-rc9.0.20200122160610-2fc03cc11c77)

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