CVE-2026-22042: Rustfs RustFS Has IAM Incorrect Authorization Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-vcwh-pff9-64cc",
  "modified" : "2026-01-08T20:36:17Z",
  "published" : "2026-01-08T20:36:17Z",
  "aliases" : [ "CVE-2026-22042" ],
  "summary" : "RustFS has IAM Incorrect Authorization in ImportIam that Allows Privilege Escalation",
  "details" : "### Summary\n\nThe `ImportIam` admin API validates permissions using **`ExportIAMAction`** instead of **`ImportIAMAction`**, allowing a principal with *export-only* IAM permissions to perform *import* operations. Since importing IAM data performs privileged **write** actions (creating/updating users, groups, policies, and service accounts), this can lead to **unauthorized IAM modification and privilege escalation**.\n\n---\n\n### Details\n\nIn `ImportIam`, the authorization check is implemented as follows:\n\n```rust\nvalidate_admin_request(\n    &req.headers,\n    &cred,\n    owner,\n    false,\n    vec![Action::AdminAction(AdminAction::ExportIAMAction)],\n).await?;\n```\n\nHowever, this code resides in the **Import IAM** operation (`struct ImportIam {}`), which performs **state-changing IAM writes**.\n\nThe expected behavior is to validate against **`AdminAction::ImportIAMAction`** (or an equivalent import-specific admin action), not `ExportIAMAction`.\n\n---\n\n### PoC\n\n**Prerequisites**\n\n1. A RustFS deployment with IAM enabled.\n2. An IAM user or role that has **Export IAM** permission but **does not** have Import IAM or full admin permissions.\n3. Access credentials for that user.\n\n**Steps**\n\n1. Create or obtain an IAM principal with permission equivalent to:\n\n   ```\n   AdminAction::ExportIAMAction\n   ```\n\n   and without Import IAM privileges.\n\n2. Prepare a valid IAM import ZIP archive containing, for example:\n\n   * A new policy granting administrative permissions\n   * A user or service account bound to that policy\n\n3. Send a request to the Import IAM endpoint (the same endpoint handled by `ImportIam::call`), authenticating with the export-only credentials.\n\n4. Observe that:\n\n   * The request passes authorization.\n   * IAM entities from the archive are created or modified successfully.\n\n**Expected Result**\n\n* The request should be rejected with an authorization error (e.g., AccessDenied).\n\n**Actual Result**\n\n* The request succeeds, and IAM state is modified.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "rustfs"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.0.0-alpha.79"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/rustfs/rustfs/security/advisories/GHSA-vcwh-pff9-64cc"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-22042"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/rustfs/rustfs"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-285" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-08T20:36:17Z",
    "nvd_published_at" : "2026-01-08T15:15:45Z"
  }
}