CVE-2026-46680: Github.com/containerd/containerd Containerd User ID Handling Bypass Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-fqw6-gf59-qr4w",
  "modified" : "2026-07-21T14:40:35Z",
  "published" : "2026-05-21T21:40:36Z",
  "aliases" : [ "CVE-2026-46680" ],
  "summary" : "containerd user ID handling bypass allows runAsNonRoot evasion",
  "details" : "### Impact\nA bug was found in containerd where containers launched with a numeric `User` directive that cannot be parsed as a 32-bit integer are incorrectly treated as a username. If a crafted image provides an `/etc/passwd` file mapping this large numeric string to root, the container ultimately runs as root (UID 0). This allows the Kubernetes `runAsNonRoot` restriction to be bypassed, causing unexpected behavior for environments that require containers to run as a non-root user.\n\n### Patches\nThis bug has been fixed in the following containerd versions:\n\n* 2.3.1\n* 2.2.4\n* 2.0.9\n* 1.7.32\n\nNote: The containerd 2.1 release has reached its [end of life](https://containerd.io/releases/#current-state-of-containerd-releases) and a fixed version is not provided.\n\nUsers should update to these versions to resolve the issue.\n\n### Workarounds\nEnsure that only trusted images are used and that only trusted users have permissions to import images. Alternatively, enforcing a specific numeric `runAsUser` in the Kubernetes Pod `securityContext` overrides the `USER` directive in the image and prevents the bypass. Newer versions of Kubernetes, starting with 1.34, also appear to enforce `runAsNonRoot` properly regardless of this bug.\n\n### Credits\nThe containerd project would like to thank Lei Wang (@ssst0n3) for responsibly disclosing this issue in accordance with the [containerd security policy](https://github.com/containerd/project/blob/main/SECURITY.md).\n\n### Resources\n* https://github.com/advisories/GHSA-265r-hfxg-fhmg (CVE-2024-40635)\n\n### For more information\n\nIf there are any questions or comments about this advisory:\n\n* Open an issue in [containerd](https://github.com/containerd/containerd/issues/new/choose)\n* Send an email to [security@containerd.io](mailto:security@containerd.io)\n\nTo report a security issue in containerd:\n* [Report a new vulnerability](https://github.com/containerd/containerd/security/advisories/new)\n* Send an email to [security@containerd.io](mailto:security@containerd.io)",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/containerd/containerd"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.7.27"
      }, {
        "fixed" : "1.7.32"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/containerd/containerd/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.0.4"
      }, {
        "fixed" : "2.0.9"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/containerd/containerd/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.1.0-beta.0"
      }, {
        "fixed" : "2.2.4"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/containerd/containerd/v2"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.3.0-beta.0"
      }, {
        "fixed" : "2.3.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/containerd/containerd/security/advisories/GHSA-fqw6-gf59-qr4w"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-46680"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/containerd/containerd"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-269", "CWE-843" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-21T21:40:36Z",
    "nvd_published_at" : "2026-07-01T18:16:32Z"
  }
}