CVE-2026-21862: Rustfs Remote Code Execution Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-fc6g-2gcp-2qrq",
  "modified" : "2026-02-03T18:55:45Z",
  "published" : "2026-02-03T17:31:41Z",
  "aliases" : [ "CVE-2026-21862" ],
  "summary" : "RustFS has SourceIp bypass via spoofed X-Forwarded-For/Real-IP headers",
  "details" : "### Summary\nIP-based access control can be bypassed: get_condition_values trusts client-supplied X-Forwarded-For/X-Real-Ip without verifying a trusted proxy, so any reachable client can spoof aws:SourceIp and satisfy IP-allowlist policies.\n\n### Details\n\n  - Vulnerable code: `rustfs/src/auth.rs:289-304` sets `remote_addr` from `X-Forwarded-For`/`X-Real-Ip`, then inserts `SourceIp` via\n    `get_source_ip_raw`, with no trust boundary or proxy validation:\n      - `let remote_addr = header.get(\"x-forwarded-for\").and_then(...).or_else(|| header.get(\"x-real-ip\")...).unwrap_or(\"127.0.0.1\");`\n      - `args.insert(\"SourceIp\", vec![get_source_ip_raw(header, remote_addr)]);`\n  - This value feeds IAM/bucket policy evaluation in `rustfs/src/storage/access.rs` (authorization path), so any request that forges the header can meet `aws:SourceIp` conditions.\n  - No authentication is required beyond the request itself; the header is taken at face value even on direct connections.\n\n\n### PoC\n\n[rustfs-auth-trusted-ip-header-spoofing-poc.tar.gz](https://github.com/user-attachments/files/24038162/rustfs-auth-trusted-ip-header-spoofing-poc.tar.gz)\n\n\nSteps (already included in `rustfs-auth-trusted-ip-header-spoofing-poc/`):\n\n  1. Start RustFS with two local volumes, e.g.:\n\n```\n     mkdir -p /tmp/rustfs-data1 /tmp/rustfs-data2\n     RUSTFS_ACCESS_KEY=devadmin RUSTFS_SECRET_KEY=devadmin \\\n       cargo run --bin rustfs -- --address 0.0.0.0:9000 \\\n       /tmp/rustfs-data1 /tmp/rustfs-data2\n```\n\n  2. From `rustfs-auth-trusted-ip-header-spoofing-poc`/, run:\n\n```\n     ENDPOINT=http://127.0.0.1:9000 make run\n```\n\n     The script:\n      - Creates bucket `rustfs-trusted-ip-poc`.\n      - Applies a bucket policy allowing `s3:ListBucket` only from `10.0.0.5/32` (`Principal: {\"AWS\":[\"*\"]},` Resource array).\n      - Sends three unauthenticated `ListBucket` calls:\n          - Baseline (no spoof) → HTTP 403.\n          - Spoofed `X-Forwarded-For: 10.0.0.5` → HTTP 200 (policy bypass).\n          - Spoofed `X-Forwarded-For: 1.2.3.4` → HTTP 403.\n      - Responses saved to `poc-baseline.xml`, `poc-spoofed.xml`, `poc-deny.xml`.\n\n\n### Impact\n\n  - Vulnerability type: Authorization bypass of IP-allowlist (`aws:SourceIp`) via header spoofing.\n  - Who is impacted: Any deployment relying on `aws:SourceIp` in IAM/bucket policies for S3 operations. Attackers with network reach to RustFS can forge forwarded-IP headers to gain list/read/write where IP restrictions were meant to block them.\n\n### Credits\nIdentified by SecMate (https://secmate.dev) automated analysis and validated during manual triage.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/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.78"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/rustfs/rustfs/security/advisories/GHSA-fc6g-2gcp-2qrq"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-21862"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rustfs/rustfs/commit/b4ba62fa3300b5b258fdc0da141481e3be7ea960"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/rustfs/rustfs"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-290" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-02-03T17:31:41Z",
    "nvd_published_at" : "2026-02-03T16:16:12Z"
  }
}