runc is a CLI tool for spawning and running containers according to the OCI specification. In versions 1.2.7, 1.3.2 and 1.4.0-rc.2, an attacker can trick runc into misdirecting writes to /proc to other procfs files through the use of a racing container with shared mounts (we have also verified this attack is possible to exploit using a standard Dockerfile with docker buildx build as that also permits triggering parallel execution of containers with custom shared mounts configured). This redirect could be through symbolic links in a tmpfs or theoretically other methods such as regular bind-mounts. While similar, the mitigation applied for the related CVE, CVE-2019-19921, was fairly limited and effectively only caused runc to verify that when LSM labels are written they are actually procfs files. This issue is fixed in versions 1.2.8, 1.3.3, and 1.4.0-rc.3.
Metrics
Affected Vendors & Products
No data.
No data.
No data.
No data.
Advisories
| Source | ID | Title |
|---|---|---|
 Github GHSA |
GHSA-cgrx-mc8f-2prm | runc container escape and denial of service due to arbitrary write gadgets and procfs write redirects |
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Thu, 06 Nov 2025 20:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | A flaw was found in runc. This attack is a more sophisticated variant of CVE-2019-16884, which was a flaw that allowed an attacker to trick runc into writing the LSM process labels for a container process into a dummy tmpfs file and thus not apply the correct LSM labels to the container process. The mitigation applied for CVE-2019-16884 was fairly limited and effectively only caused runc to verify that when we write LSM labels that those labels are actual procfs files. | runc is a CLI tool for spawning and running containers according to the OCI specification. In versions 1.2.7, 1.3.2 and 1.4.0-rc.2, an attacker can trick runc into misdirecting writes to /proc to other procfs files through the use of a racing container with shared mounts (we have also verified this attack is possible to exploit using a standard Dockerfile with docker buildx build as that also permits triggering parallel execution of containers with custom shared mounts configured). This redirect could be through symbolic links in a tmpfs or theoretically other methods such as regular bind-mounts. While similar, the mitigation applied for the related CVE, CVE-2019-19921, was fairly limited and effectively only caused runc to verify that when LSM labels are written they are actually procfs files. This issue is fixed in versions 1.2.8, 1.3.3, and 1.4.0-rc.3. |
| Title | runc: opencontainers/selinux: container escape and denial of service due to arbitrary write gadgets and procfs write redirects | runc: LSM labels can be bypassed with malicious config using dummy procfs files |
| Weaknesses | CWE-363 CWE-61 |
|
| References |
|
|
| Metrics |
cvssV4_0
|
Thu, 06 Nov 2025 12:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | A flaw was found in runc. This attack is a more sophisticated variant of CVE-2019-16884, which was a flaw that allowed an attacker to trick runc into writing the LSM process labels for a container process into a dummy tmpfs file and thus not apply the correct LSM labels to the container process. The mitigation applied for CVE-2019-16884 was fairly limited and effectively only caused runc to verify that when we write LSM labels that those labels are actual procfs files. | |
| Title | runc: opencontainers/selinux: container escape and denial of service due to arbitrary write gadgets and procfs write redirects | |
| Weaknesses | CWE-59 | |
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
MITRE
Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2025-11-06T20:23:36.237Z
Reserved: 2025-06-20T17:42:25.708Z
Link: CVE-2025-52881
Vulnrichment
No data.
NVD
No data.
Redhat
OpenCVE Enrichment
No data.