{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-40594",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-21T18:01:27.681393Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-21T18:01:30.556Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/pyload/pyload/security/advisories/GHSA-mp82-fmj6-f22v"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "pyload",
          "vendor": "pyload",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.5.0b3.dev98"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "pyLoad is a free and open-source download manager written in Python. Prior to 0.5.0b3.dev98, the set_session_cookie_secure before_request handler in src/pyload/webui/app/__init__.py reads the X-Forwarded-Proto header from any HTTP request without validating that the request originates from a trusted proxy, then mutates the global Flask configuration SESSION_COOKIE_SECURE on every request. Because pyLoad uses the multi-threaded Cheroot WSGI server (request_queue_size=512), this creates a race condition where an attacker\u0027s request can influence the Secure flag on other users\u0027 session cookies \u2014 either downgrading cookie security behind a TLS proxy or causing a session denial-of-service on plain HTTP deployments. This vulnerability is fixed in 0.5.0b3.dev98."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "LOW",
            "baseScore": 4.8,
            "baseSeverity": "MEDIUM",
            "confidentialityImpact": "LOW",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-346",
              "description": "CWE-346: Origin Validation Error",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-21T17:14:03.627Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/pyload/pyload/security/advisories/GHSA-mp82-fmj6-f22v",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/pyload/pyload/security/advisories/GHSA-mp82-fmj6-f22v"
        }
      ],
      "source": {
        "advisory": "GHSA-mp82-fmj6-f22v",
        "discovery": "UNKNOWN"
      },
      "title": "pyLoad: Session Cookie Security Downgrade via Untrusted X-Forwarded-Proto Header Spoofing (Global State Race Condition)"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-40594",
    "datePublished": "2026-04-21T17:14:03.627Z",
    "dateReserved": "2026-04-14T14:07:59.641Z",
    "dateUpdated": "2026-04-21T18:01:30.556Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 0.5.0b3.dev97"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "pyload-ng"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.5.0b3.dev98"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-40594"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-346"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-16T01:20:49Z",
    "nvd_published_at": "2026-04-21T18:16:51Z",
    "severity": "MODERATE"
  },
  "details": "## Summary\n\nThe `set_session_cookie_secure` `before_request` handler in `src/pyload/webui/app/__init__.py` reads the `X-Forwarded-Proto` header from any HTTP request without validating that the request originates from a trusted proxy, then mutates the **global** Flask configuration `SESSION_COOKIE_SECURE` on every request. Because pyLoad uses the multi-threaded Cheroot WSGI server (`request_queue_size=512`), this creates a race condition where an attacker\u0027s request can influence the `Secure` flag on other users\u0027 session cookies \u2014 either downgrading cookie security behind a TLS proxy or causing a session denial-of-service on plain HTTP deployments.\n\n## Details\n\nThe vulnerable code is in `src/pyload/webui/app/__init__.py:75-84`:\n\n```python\n# Dynamically set SESSION_COOKIE_SECURE according to the value of X-Forwarded-Proto\n# TODO: Add trusted proxy check\n@app.before_request\ndef set_session_cookie_secure():\n    x_forwarded_proto = flask.request.headers.get(\"X-Forwarded-Proto\", \"\")\n    is_secure = (\n        x_forwarded_proto.split(\u0027,\u0027)[0].strip() == \"https\" or\n        app.config[\"PYLOAD_API\"].get_config_value(\"webui\", \"use_ssl\")\n    )\n    flask.current_app.config[\u0027SESSION_COOKIE_SECURE\u0027] = is_secure\n```\n\nThe root cause has two components:\n\n1. **No origin validation (CWE-346):** The `X-Forwarded-Proto` header is read from any client request. This header is only trustworthy when set by a known reverse proxy. Without `ProxyFix` middleware or a trusted proxy allowlist, any client can spoof it. The code itself acknowledges this with the TODO on line 76.\n\n2. **Global state mutation in a multi-threaded server:** `flask.current_app.config[\u0027SESSION_COOKIE_SECURE\u0027]` is application-wide shared state. When Thread A (attacker) writes `False` to this config, Thread B (victim) may read `False` when Flask\u0027s `save_session()` runs in the after_request phase, producing a `Set-Cookie` response without the `Secure` flag.\n\nThe Cheroot WSGI server is configured with `request_queue_size=512` in `src/pyload/webui/webserver_thread.py:46`, confirming concurrent multi-threaded request processing.\n\nNo `ProxyFix` or equivalent middleware is configured anywhere in the codebase (confirmed via codebase-wide search).\n\n## PoC\n\n**Attack Path 1 \u2014 Cookie Security Downgrade (behind TLS-terminating proxy, `use_ssl=False`):**\n\nAn attacker with direct access to the backend (e.g., in a containerized/Kubernetes deployment) sends concurrent requests to keep `SESSION_COOKIE_SECURE` set to `False`:\n\n```bash\n# Attacker floods backend directly, bypassing TLS proxy\nfor i in $(seq 1 200); do\n  curl -s -H \u0027X-Forwarded-Proto: http\u0027 http://pyload-backend:8000/ \u0026\ndone\n\n# Meanwhile, a legitimate user behind the TLS proxy receives a session cookie\n# During the race window, their Set-Cookie header lacks the Secure flag\n# The cookie is then vulnerable to interception over plain HTTP\n```\n\n**Attack Path 2 \u2014 Session Denial of Service (default plain HTTP deployment):**\n\n```bash\n# Attacker causes SESSION_COOKIE_SECURE=True on a plain HTTP server\nfor i in $(seq 1 200); do\n  curl -s -H \u0027X-Forwarded-Proto: https\u0027 http://localhost:8000/ \u0026\ndone\n\n# Concurrent legitimate users receive Set-Cookie with Secure flag\n# Browser refuses to send Secure cookies over HTTP\n# Users\u0027 sessions silently break \u2014 they appear logged out\n```\n\nThe second attack path works against the default configuration (`use_ssl=False`) and requires no special network position.\n\n## Impact\n\n- **Session cookie exposure (Attack Path 1):** When deployed behind a TLS-terminating proxy, an attacker can cause session cookies to be issued without the `Secure` flag. If the victim\u0027s browser subsequently makes an HTTP request (e.g., via a mixed-content link or downgrade attack), the session cookie is transmitted in cleartext, enabling session hijacking.\n\n- **Session denial of service (Attack Path 2):** On default plain HTTP deployments, an attacker can continuously set `SESSION_COOKIE_SECURE=True`, causing browsers to refuse sending session cookies back to the server. This silently breaks all concurrent users\u0027 sessions with no user-visible error message, only a redirect to login.\n\n- **No authentication required:** Both attack paths are fully unauthenticated \u2014 the `before_request` handler fires before any auth checks.\n\n## Recommended Fix\n\nReplace the global config mutation with per-response cookie handling, and add proxy validation:\n\n```python\n# Option A: Set Secure flag per-response instead of mutating global config\n@app.after_request\ndef set_session_cookie_secure(response):\n    # Only trust X-Forwarded-Proto if ProxyFix is configured\n    is_secure = app.config[\"PYLOAD_API\"].get_config_value(\"webui\", \"use_ssl\")\n    if \u0027Set-Cookie\u0027 in response.headers:\n        # Modify cookie flags per-response, not global config\n        cookies = response.headers.getlist(\u0027Set-Cookie\u0027)\n        response.headers.remove(\u0027Set-Cookie\u0027)\n        for cookie in cookies:\n            if is_secure and \u0027Secure\u0027 not in cookie:\n                cookie += \u0027; Secure\u0027\n            response.headers.add(\u0027Set-Cookie\u0027, cookie)\n    return response\n\n# Option B (preferred): Use Werkzeug\u0027s ProxyFix with explicit trust\nfrom werkzeug.middleware.proxy_fix import ProxyFix\n\n# In App.__new__, before returning:\nif trusted_proxy_count:  # from config\n    app.wsgi_app = ProxyFix(app.wsgi_app, x_proto=trusted_proxy_count)\n# Then set SESSION_COOKIE_SECURE once at startup based on use_ssl config,\n# and let ProxyFix handle X-Forwarded-Proto transparently\n```\n\nAt minimum, remove the `before_request` handler entirely and set `SESSION_COOKIE_SECURE` once at startup (line 130 already does this in `_configure_session`). The dynamic per-request adjustment is the root cause of both the spoofing and the race condition.",
  "id": "GHSA-mp82-fmj6-f22v",
  "modified": "2026-04-27T16:15:46Z",
  "published": "2026-04-16T01:20:49Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pyload/pyload/security/advisories/GHSA-mp82-fmj6-f22v"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40594"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pyload/pyload"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "pyLoad has a Session Cookie Security Downgrade via Untrusted X-Forwarded-Proto Header Spoofing (Global State Race Condition)"
}