GHSA-RG2X-37C3-W2RH

Vulnerability from github – Published: 2026-05-18 17:53 – Updated: 2026-06-12 21:59
VLAI
Summary
Docker: Race condition in docker cp allows bind mount redirection to host path
Details

Summary

A race condition during docker cp mount setup allows a malicious container to redirect a bind mount target to an arbitrary host path, potentially overwriting host files or causing denial of service.

Details

When copying files into a container, the daemon sets up a temporary filesystem view by bind-mounting volumes into a private mount namespace. During this setup, the mount destination is created inside the container root and then a bind mount is attached using the container-relative path resolved to an absolute host path.

Between mountpoint creation and the mount() syscall, a process running inside the container can replace the destination (or a parent path component) with a symlink pointing to an arbitrary location on the host. The mount() syscall follows the symlink, causing the volume to be bind-mounted onto an arbitrary host path instead of the intended container path.

Impact

A malicious container can redirect a volume bind mount to an arbitrary host path. The impact depends on the volume content and mount options:

  • If the volume is writable, arbitrary host files at the redirected path could be overwritten with the volume's contents.
  • If the volume is read-only, the host path is masked by the mount for the duration of the operation, causing denial of service.
  • In all cases the mount is temporary (torn down after the docker cp completes), but the effects of any writes persist.

Conditions for exploitation

  • A container must have at least one volume mount.
  • A process inside the container must be able to rapidly create and swap symlinks at the volume mount destination path.
  • An operator must initiate a docker cp into that container, or call the PUT /containers/{id}/archive or HEAD /containers/{id}/archive API endpoints.

Not affected

  • Containers that do not have volume mounts are not affected, as the race occurs during volume bind-mount setup.

Workarounds

  • Only run containers from trusted images.
  • Avoid using docker cp with untrusted running containers.
  • Use authorization plugins to restrict access to the archive API endpoints (PUT /containers/{id}/archive, HEAD /containers/{id}/archive).
Severity
7.2 (High)
CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:C/C:N/I:H/A:H
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/docker/docker"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "28.5.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/moby/moby/v2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.0.0-beta.14"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/moby/moby"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "last_affected": "28.5.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-42306"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367",
      "CWE-61"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-18T17:53:08Z",
    "nvd_published_at": "2026-06-12T19:16:27Z",
    "severity": "HIGH"
  },
  "details": "## Summary\n\nA race condition during `docker cp` mount setup allows a malicious container to redirect a bind mount target to an arbitrary host path, potentially overwriting host files or causing denial of service.\n\n## Details\n\nWhen copying files into a container, the daemon sets up a temporary filesystem view by bind-mounting volumes into a private mount namespace. During this setup, the mount destination is created inside the container root and then a bind mount is attached using the container-relative path resolved to an absolute host path.\n\nBetween mountpoint creation and the `mount()` syscall, a process running inside the container can replace the destination (or a parent path component) with a symlink pointing to an arbitrary location on the host. The `mount()` syscall follows the symlink, causing the volume to be bind-mounted onto an arbitrary host path instead of the intended container path.\n\n## Impact\n\nA malicious container can redirect a volume bind mount to an arbitrary host path. The impact depends on the volume content and mount options:\n\n- If the volume is writable, arbitrary host files at the redirected path could be overwritten with the volume\u0027s contents.\n- If the volume is read-only, the host path is masked by the mount for the duration of the operation, causing denial of service.\n- In all cases the mount is temporary (torn down after the `docker cp` completes), but the effects of any writes persist.\n\n### Conditions for exploitation\n\n- A container must have at least one volume mount.\n- A process inside the container must be able to rapidly create and swap symlinks at the volume mount destination path.\n- An operator must initiate a `docker cp` into that container, or call the `PUT /containers/{id}/archive` or `HEAD /containers/{id}/archive` API endpoints.\n\n### Not affected\n\n- Containers that do not have volume mounts are not affected, as the race occurs during volume bind-mount setup.\n\n## Workarounds\n\n- Only run containers from trusted images.\n- Avoid using `docker cp` with untrusted running containers.\n- Use authorization plugins to restrict access to the archive API endpoints (`PUT /containers/{id}/archive`, `HEAD /containers/{id}/archive`).",
  "id": "GHSA-rg2x-37c3-w2rh",
  "modified": "2026-06-12T21:59:32Z",
  "published": "2026-05-18T17:53:08Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/moby/moby/security/advisories/GHSA-rg2x-37c3-w2rh"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42306"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/moby/moby"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:C/C:N/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Docker: Race condition in docker cp allows bind mount redirection to host path"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON
How durations are calculated

Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.