container escape via 'masked path' abuse due to mount race conditions
CVE: CVE-2025-31133
Component: runc
CWE: CWE-59
Severity: Important
CVSS v3: 8.0/AV:L/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H
Release date: 2025-11-05T00:00:00+00:00

A flaw was found in runc. This flaw exploits an issue with how masked paths are implementedin runc. When masking files, runc will bind-mount the container's /dev/null inode on top of the file. However, if an attacker can replace /dev/null with a symlink to some other procfs file, runc will instead bind-mount the symlink target read-write.

Statement: Red Hat considers this as an Important flaw since the impact is limited to local attack with minimal privileges in order to jeopardize the environment.

Remediation:
For OpenShift Container Platform 4.12 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata
update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.12/html/release_notes
For OpenShift Container Platform 4.13 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.13/html/release_notes
For OpenShift Container Platform 4.14 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.14/html/release_notes/
For OpenShift Container Platform 4.15 see the following documentation,
which will be updated shortly for this release, for important instructions
on how to upgrade your cluster and fully apply this asynchronous errata
update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.15/html/release_notes/
For OpenShift Container Platform 4.16 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.16/html/release_notes/
For OpenShift Container Platform 4.18 see the following documentation,
which will be updated shortly for this release, for important instructions
on how to upgrade your cluster and fully apply this asynchronous errata
update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.18/html/release_notes/
For OpenShift Container Platform 4.13 see the following documentation,
which will be updated shortly for this release, for important instructions
on how to upgrade your cluster and fully apply this asynchronous errata
update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.13/html/release_notes

You may download the oc tool and use it to inspect release image metadata
for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests
may be found at
https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags.

      The sha value for the release is as follows:

      (For x86_64 architecture)
      The image digest is sha256:384dcc2b7dde97674e4197b6e4130268adc2b00a94908aa9220a4061aa1030ac

All OpenShift Container Platform 4.13 users are advised to upgrade to these
updated packages and images when they are available in the appropriate
release channel. To check for available updates, use the OpenShift CLI (oc)
or web console. Instructions for upgrading a cluster are available at
https://docs.redhat.com/en/documentation/openshift_container_platform/4.13/html-single/updating_clusters/index#updating-cluster-within-minor.
For OpenShift Container Platform 4.15 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.15/html/release_notes/

You may download the oc tool and use it to inspect release image metadata for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests may be found at https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags.

The sha values for the release are as follows:

      (For x86_64 architecture)
      The image digest is sha256:39236e073ff4b62406a472178263fd2220b0f544c3fd26036120b470596fa255

      (For s390x architecture)
      The image digest is sha256:f94d7fce531623dd0d1d4b5fe1c299eba7152676306ed2e9ea3c7fe17b4ad5ee

      (For ppc64le architecture)
      The image digest is sha256:5cdc5d1a0cb3b990afbaa8d1559abf87d9194c375541f27689aa974c1336d9eb

      (For aarch64 architecture)
      The image digest is sha256:584bb60432b0460d97b9624a3cb1c625469534ac44dedb618f14834161c2d448

All OpenShift Container Platform 4.15 users are advised to upgrade to these updated packages and images when they are available in the appropriate release channel. To check for available updates, use the OpenShift CLI (oc) or web console. Instructions for upgrading a cluster are available at https://docs.redhat.com/en/documentation/openshift_container_platform/4.15/html-single/updating_clusters/index#updating-cluster-cli.
For OpenShift Container Platform 4.16 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.16/html/release_notes/

You may download the oc tool and use it to inspect release image metadata for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests may be found at https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags.

The sha values for the release are as follows:

      (For x86_64 architecture)
      The image digest is sha256:fe82edf8318eb10aac27fbc005ccee485a6e92734a0241cfa74a5b5ad4f9cc04

      (For s390x architecture)
      The image digest is sha256:91659a7217d7007c7c89424491935a4cbff57ff651ca183dfc9abe51cad37315
      (For ppc64le architecture)
      The image digest is sha256:1b195e402933e9d828a9d48ca1e0ce5835686cffda64a3910efba819de61b829
      (For aarch64 architecture)
      The image digest is sha256:d9ad3b1418d7e8c9c5a38f2b378d944c5af7ed31253fd00025d6ac5b340ada50

All OpenShift Container Platform 4.16 users are advised to upgrade to these updated packages and images when they are available in the appropriate release channel. To check for available updates, use the OpenShift CLI (oc) or web console. Instructions for upgrading a cluster are available at https://docs.redhat.com/en/documentation/openshift_container_platform/4.16/html-single/updating_clusters/index#updating-cluster-cli.
For OpenShift Container Platform 4.17 see the following documentation,
which will be updated shortly for this release, for important instructions
on how to upgrade your cluster and fully apply this asynchronous errata
update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.17/html/release_notes/
For OpenShift Container Platform 4.18 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update:

https://docs.redhat.com/en/documentation/openshift_container_platform/4.18/html/release_notes/

You may download the oc tool and use it to inspect release image metadata for x86_64, s390x, ppc64le, and aarch64 architectures. The image digests may be found at https://quay.io/repository/openshift-release-dev/ocp-release?tab=tags.

The sha values for the release are as follows:

      (For x86_64 architecture)
      The image digest is sha256:8c885ea0b3c5124989f0a9b93eba98eb9fca6bbd0262772d85d90bf713a4d572

      (For s390x architecture)
      The image digest is sha256:d0c9986fa3f054dc1f97289ee8869ec874ae191e86bf26c99c9ff0d945a09daa

      (For ppc64le architecture)
      The image digest is sha256:9f37a92c84e0e89378b1917cf3798331a39ef8f372169d985c1e2e48fbebba5f

      (For aarch64 architecture)
      The image digest is sha256:a6eefbbea0e6142de87f9894df435c433fe8153b9c522ab81ce28e3667de885d

All OpenShift Container Platform 4.18 users are advised to upgrade to these updated packages and images when they are available in the appropriate release channel. To check for available updates, use the OpenShift CLI (oc) or web console. Instructions for upgrading a cluster are available at https://docs.redhat.com/en/documentation/openshift_container_platform/4.18/html-single/updating_clusters/index#updating-cluster-cli.
Before applying this update, make sure all previously released errata relevant
to your system have been applied.

For details on how to apply this update, refer to:

https://access.redhat.com/articles/11258
Potential mitigations for this issue include:

* Using user namespaces, with the host root user not mapped into the container's namespace. procfs file permissions are managed using Unix
DAC and thus user namespaces stop a container process from being able to write to them.

* Not running as a root user in the container (this includes disabling setuid binaries with noNewPrivileges). As above, procfs file permissions are managed using Unix DAC and thus non-root users cannot write to them.

* Depending on the maskedPath configuration (the default configuratio nonly masks paths in /proc and /sys), using an AppArmor that blocks unexpectedwrites to any maskedPaths (as is the case with the defaultprofile used by Docker and Podman) will block attempts to exploit this issue. However, CVE-2025-52881 allows an attacker to bypass LSMlabels, and so this mitigation is not helpful when considered incombination with CVE-2025-52881.