{"id":"CVE-2025-53890","aliases":["EUVD-2025-21406","GHSA-8w3f-4r8f-pf53","PYSEC-2026-496"],"status":"published","title":"pyLoad vulnerable to remote code execution through js2py onCaptchaResult","description":"pyload is an open-source Download Manager written in pure Python. An unsafe JavaScript evaluation vulnerability in pyLoad’s CAPTCHA processing code allows unauthenticated remote attackers to execute arbitrary code in the client browser and potentially the backend server. Exploitation requires no user interaction or authentication and can result in session hijacking, credential theft, and full system remote code execution. Commit 909e5c97885237530d1264cfceb5555870eb9546, the patch for the issue, is included in version 0.5.0b3.dev89.","severity":{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.01298,"percentile":0.70638,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-79","CWE-94"],"published":"2025-07-14T23:57:09Z","modified":"2026-10-28T02:30:39Z","fixes":[{"ecosystem":"PyPI","package":"pyload-ng","fixed_in":["0.20"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"pyload-ng","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.20"}]}]},{"source":"osv","ecosystem":"PyPI","package":"pyload-ng","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.20"}]}],"versions":["0.5.0a5.dev528","0.5.0a5.dev532","0.5.0a5.dev535","0.5.0a5.dev536","0.5.0a5.dev537","0.5.0a5.dev539","0.5.0a5.dev540","0.5.0a5.dev545","0.5.0a5.dev562","0.5.0a5.dev564","0.5.0a5.dev565","0.5.0a6.dev570","0.5.0a6.dev578","0.5.0a6.dev587","0.5.0a7.dev596","0.5.0a8.dev602","0.5.0a9.dev615","0.5.0a9.dev629","0.5.0a9.dev632","0.5.0a9.dev641","0.5.0a9.dev643","0.5.0a9.dev655","0.5.0a9.dev806","0.5.0b1.dev1","0.5.0b1.dev2","0.5.0b1.dev3","0.5.0b1.dev4","0.5.0b1.dev5","0.5.0b2.dev10","0.5.0b2.dev11","0.5.0b2.dev12","0.5.0b2.dev9","0.5.0b3.dev100","0.5.0b3.dev101","0.5.0b3.dev13","0.5.0b3.dev14","0.5.0b3.dev17","0.5.0b3.dev18","0.5.0b3.dev19","0.5.0b3.dev20","0.5.0b3.dev21","0.5.0b3.dev22","0.5.0b3.dev24","0.5.0b3.dev26","0.5.0b3.dev27","0.5.0b3.dev28","0.5.0b3.dev29","0.5.0b3.dev30","0.5.0b3.dev31","0.5.0b3.dev32","0.5.0b3.dev33","0.5.0b3.dev34","0.5.0b3.dev35","0.5.0b3.dev38","0.5.0b3.dev39","0.5.0b3.dev40","0.5.0b3.dev41","0.5.0b3.dev42","0.5.0b3.dev43","0.5.0b3.dev44","0.5.0b3.dev45","0.5.0b3.dev46","0.5.0b3.dev47","0.5.0b3.dev48","0.5.0b3.dev49","0.5.0b3.dev50","0.5.0b3.dev51","0.5.0b3.dev52","0.5.0b3.dev53","0.5.0b3.dev54","0.5.0b3.dev57","0.5.0b3.dev60","0.5.0b3.dev62","0.5.0b3.dev64","0.5.0b3.dev65","0.5.0b3.dev66","0.5.0b3.dev67","0.5.0b3.dev68","0.5.0b3.dev69","0.5.0b3.dev70","0.5.0b3.dev71","0.5.0b3.dev72","0.5.0b3.dev73","0.5.0b3.dev74","0.5.0b3.dev75","0.5.0b3.dev76","0.5.0b3.dev77","0.5.0b3.dev78","0.5.0b3.dev79","0.5.0b3.dev80","0.5.0b3.dev81","0.5.0b3.dev82","0.5.0b3.dev85","0.5.0b3.dev87","0.5.0b3.dev88","0.5.0b3.dev89","0.5.0b3.dev90","0.5.0b3.dev91","0.5.0b3.dev92","0.5.0b3.dev93","0.5.0b3.dev94","0.5.0b3.dev95","0.5.0b3.dev96","0.5.0b3.dev97","0.5.0b3.dev98","0.5.0b3.dev99"]},{"source":"osv","ecosystem":"PyPI","package":"pyload-ng","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"0.20"}]}],"versions":["0.5.0a5.dev528","0.5.0a5.dev532","0.5.0a5.dev535","0.5.0a5.dev536","0.5.0a5.dev537","0.5.0a5.dev539","0.5.0a5.dev540","0.5.0a5.dev545","0.5.0a5.dev562","0.5.0a5.dev564","0.5.0a5.dev565","0.5.0a6.dev570","0.5.0a6.dev578","0.5.0a6.dev587","0.5.0a7.dev596","0.5.0a8.dev602","0.5.0a9.dev615","0.5.0a9.dev629","0.5.0a9.dev632","0.5.0a9.dev641","0.5.0a9.dev643","0.5.0a9.dev655","0.5.0a9.dev806","0.5.0b1.dev1","0.5.0b1.dev2","0.5.0b1.dev3","0.5.0b1.dev4","0.5.0b1.dev5","0.5.0b2.dev10","0.5.0b2.dev11","0.5.0b2.dev12","0.5.0b2.dev9","0.5.0b3.dev100","0.5.0b3.dev101","0.5.0b3.dev13","0.5.0b3.dev14","0.5.0b3.dev17","0.5.0b3.dev18","0.5.0b3.dev19","0.5.0b3.dev20","0.5.0b3.dev21","0.5.0b3.dev22","0.5.0b3.dev24","0.5.0b3.dev26","0.5.0b3.dev27","0.5.0b3.dev28","0.5.0b3.dev29","0.5.0b3.dev30","0.5.0b3.dev31","0.5.0b3.dev32","0.5.0b3.dev33","0.5.0b3.dev34","0.5.0b3.dev35","0.5.0b3.dev38","0.5.0b3.dev39","0.5.0b3.dev40","0.5.0b3.dev41","0.5.0b3.dev42","0.5.0b3.dev43","0.5.0b3.dev44","0.5.0b3.dev45","0.5.0b3.dev46","0.5.0b3.dev47","0.5.0b3.dev48","0.5.0b3.dev49","0.5.0b3.dev50","0.5.0b3.dev51","0.5.0b3.dev52","0.5.0b3.dev53","0.5.0b3.dev54","0.5.0b3.dev57","0.5.0b3.dev60","0.5.0b3.dev62","0.5.0b3.dev64","0.5.0b3.dev65","0.5.0b3.dev66","0.5.0b3.dev67","0.5.0b3.dev68","0.5.0b3.dev69","0.5.0b3.dev70","0.5.0b3.dev71","0.5.0b3.dev72","0.5.0b3.dev73","0.5.0b3.dev74","0.5.0b3.dev75","0.5.0b3.dev76","0.5.0b3.dev77","0.5.0b3.dev78","0.5.0b3.dev79","0.5.0b3.dev80","0.5.0b3.dev81","0.5.0b3.dev82","0.5.0b3.dev85","0.5.0b3.dev87","0.5.0b3.dev88","0.5.0b3.dev89","0.5.0b3.dev90","0.5.0b3.dev91","0.5.0b3.dev92","0.5.0b3.dev93","0.5.0b3.dev94","0.5.0b3.dev95","0.5.0b3.dev96","0.5.0b3.dev97","0.5.0b3.dev98","0.5.0b3.dev99"]}],"products":[{"vendor":"pyload","product":"pyload"}],"references":[{"url":"https://github.com/pyload/pyload/security/advisories/GHSA-8w3f-4r8f-pf53","tags":["x_refsource_CONFIRM","exploit","advisory","web"]},{"url":"https://github.com/pyload/pyload/pull/4586","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/pyload/pyload/commit/909e5c97885237530d1264cfceb5555870eb9546","tags":["x_refsource_MISC","fix","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-53890","tags":["advisory"]},{"url":"https://github.com/advisories/GHSA-8w3f-4r8f-pf53","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/53xxx/CVE-2025-53890.json","tags":["advisory"]},{"url":"https://github.com/pyload/pyload","tags":["package"]},{"url":"https://pypi.org/project/pyload-ng","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2025-53890","title":"pyLoad vulnerable to remote code execution through js2py onCaptchaResult","description":"pyload is an open-source Download Manager written in pure Python. An unsafe JavaScript evaluation vulnerability in pyLoad’s CAPTCHA processing code allows unauthenticated remote attackers to execute arbitrary code in the client browser and potentially the backend server. Exploitation requires no user interaction or authentication and can result in session hijacking, credential theft, and full system remote code execution. Commit 909e5c97885237530d1264cfceb5555870eb9546, the patch for the issue, is included in version 0.5.0b3.dev89.","status":"published","published":"2025-07-14T23:57:09.574Z","modified":"2025-07-15T19:48:50.099Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"cna"}],"cwes":["CWE-94"],"updated_at":"2026-11-02T14:32:48.853452Z"}],"euvd":[{"id":"EUVD-2025-21406","description":"pyload is an open-source Download Manager written in pure Python. An unsafe JavaScript evaluation vulnerability in pyLoad’s CAPTCHA processing code allows unauthenticated remote attackers to execute arbitrary code in the client browser and potentially the backend server. Exploitation requires no user interaction or authentication and can result in session hijacking, credential theft, and full system remote code execution. Commit 909e5c97885237530d1264cfceb5555870eb9546, the patch for the issue, is included in version 0.5.0b3.dev89.","status":"published","published":"2025-07-14T23:57:09Z","modified":"2025-07-15T19:48:50Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T20:32:07.830372Z"}],"ghsa":[{"id":"GHSA-8w3f-4r8f-pf53","title":"pyLoad vulnerable to XSS through insecure CAPTCHA ","description":"#### Summary\nAn unsafe JavaScript evaluation vulnerability in pyLoad’s CAPTCHA processing code allows **unauthenticated remote attackers** to execute **arbitrary code** in the client browser and potentially the backend server. Exploitation requires no user interaction or authentication and can result in session hijacking, credential theft, and full system rce.\n\n\n\n#### Details\nThe vulnerable code resides in \n```javascript\nfunction onCaptchaResult(result) {\n    eval(result); // Direct execution of attacker-controlled input\n}\n```\n\n* The `onCaptchaResult()` function directly passes CAPTCHA results (sent from the user) into `eval()`\n* No sanitization or validation is performed on this input\n* A malicious CAPTCHA result can include JavaScript such as `fetch()` or `child_process.exec()` in environments using NodeJS\n* Attackers can fully hijack sessions and pivot to remote code execution on the server if the environment allows it\n\n\n\n### Reproduction Methods\n1. **Official Source Installation**:\n```bash\ngit clone https://github.com/pyload/pyload\ncd pyload\ngit checkout 0.4.20\npython -m pip install -e .\npyload --userdir=/tmp/pyload\n```\n\n2. **Virtual Environment**:\n```bash\npython -m venv pyload-env\nsource pyload-env/bin/activate\npip install pyload==0.4.20\npyload\n```\n\n## CAPTCHA Endpoint Verification\n\n\n**Technical Clarification**:  \n1. The vulnerable endpoint is actually:\n   ```\n   /interactive/captcha\n   ```\n\n2. Complete PoC Request:\n```http\nPOST /interactive/captcha HTTP/1.1\nHost: localhost:8000\nContent-Type: application/x-www-form-urlencoded\n\ncid=123\u0026response=1%3Balert(document.cookie)\n```\n\n3. Curl Command Correction:\n```bash\ncurl -X POST \"http://localhost:8000/interactive/captcha\" \\\n  -d \"cid=123\u0026response=1%3Balert(document.cookie)\"\n```\n\n\n1. **Vulnerable Code Location**:  \n   The eval() vulnerability is confirmed in:\n   ```\n   src/pyload/webui/app/static/js/captcha-interactive.user.js\n   ```\n\n\n\n### **Resources**\n\n1. https://github.com/pyload/pyload/commit/909e5c97885237530d1264cfceb5555870eb9546\n2. [OWASP: Avoid `eval()`](https://cheatsheetseries.owasp.org/cheatsheets/JavaScript_Security_Cheat_Sheet.html#eval)\n3. [#4586](https://github.com/pyload/pyload/pull/4586)","status":"published","published":"2025-07-15T15:38:10Z","modified":"2025-07-15T15:38:13Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-79","CWE-94"],"updated_at":"2026-11-02T14:38:49.837727Z"}],"nvd":[{"id":"CVE-2025-53890","description":"pyload is an open-source Download Manager written in pure Python. An unsafe JavaScript evaluation vulnerability in pyLoad’s CAPTCHA processing code allows unauthenticated remote attackers to execute arbitrary code in the client browser and potentially the backend server. Exploitation requires no user interaction or authentication and can result in session hijacking, credential theft, and full system remote code execution. Commit 909e5c97885237530d1264cfceb5555870eb9546, the patch for the issue, is included in version 0.5.0b3.dev89.","status":"published","published":"2025-07-15T00:15:24.15Z","modified":"2026-06-17T09:39:05.117Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"secondary"}],"cwes":["CWE-94"],"updated_at":"2026-11-02T14:11:18.285862Z"}],"osv":[{"id":"CVE-2025-53890","title":"pyLoad vulnerable to remote code execution through js2py onCaptchaResult","description":"pyload is an open-source Download Manager written in pure Python. An unsafe JavaScript evaluation vulnerability in pyLoad’s CAPTCHA processing code allows unauthenticated remote attackers to execute arbitrary code in the client browser and potentially the backend server. Exploitation requires no user interaction or authentication and can result in session hijacking, credential theft, and full system remote code execution. Commit 909e5c97885237530d1264cfceb5555870eb9546, the patch for the issue, is included in version 0.5.0b3.dev89.","status":"published","published":"2025-07-14T23:57:09.574Z","modified":"2026-10-28T02:30:39.401779876Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-94"],"updated_at":"2026-11-02T15:44:50.45326Z"},{"id":"GHSA-8w3f-4r8f-pf53","title":"pyLoad vulnerable to XSS through insecure CAPTCHA ","description":"#### Summary\nAn unsafe JavaScript evaluation vulnerability in pyLoad’s CAPTCHA processing code allows **unauthenticated remote attackers** to execute **arbitrary code** in the client browser and potentially the backend server. Exploitation requires no user interaction or authentication and can result in session hijacking, credential theft, and full system rce.\n\n\n\n#### Details\nThe vulnerable code resides in \n```javascript\nfunction onCaptchaResult(result) {\n    eval(result); // Direct execution of attacker-controlled input\n}\n```\n\n* The `onCaptchaResult()` function directly passes CAPTCHA results (sent from the user) into `eval()`\n* No sanitization or validation is performed on this input\n* A malicious CAPTCHA result can include JavaScript such as `fetch()` or `child_process.exec()` in environments using NodeJS\n* Attackers can fully hijack sessions and pivot to remote code execution on the server if the environment allows it\n\n\n\n### Reproduction Methods\n1. **Official Source Installation**:\n```bash\ngit clone https://github.com/pyload/pyload\ncd pyload\ngit checkout 0.4.20\npython -m pip install -e .\npyload --userdir=/tmp/pyload\n```\n\n2. **Virtual Environment**:\n```bash\npython -m venv pyload-env\nsource pyload-env/bin/activate\npip install pyload==0.4.20\npyload\n```\n\n## CAPTCHA Endpoint Verification\n\n\n**Technical Clarification**:  \n1. The vulnerable endpoint is actually:\n   ```\n   /interactive/captcha\n   ```\n\n2. Complete PoC Request:\n```http\nPOST /interactive/captcha HTTP/1.1\nHost: localhost:8000\nContent-Type: application/x-www-form-urlencoded\n\ncid=123\u0026response=1%3Balert(document.cookie)\n```\n\n3. Curl Command Correction:\n```bash\ncurl -X POST \"http://localhost:8000/interactive/captcha\" \\\n  -d \"cid=123\u0026response=1%3Balert(document.cookie)\"\n```\n\n\n1. **Vulnerable Code Location**:  \n   The eval() vulnerability is confirmed in:\n   ```\n   src/pyload/webui/app/static/js/captcha-interactive.user.js\n   ```\n\n\n\n### **Resources**\n\n1. https://github.com/pyload/pyload/commit/909e5c97885237530d1264cfceb5555870eb9546\n2. [OWASP: Avoid `eval()`](https://cheatsheetseries.owasp.org/cheatsheets/JavaScript_Security_Cheat_Sheet.html#eval)\n3. [#4586](https://github.com/pyload/pyload/pull/4586)","status":"published","published":"2025-07-15T15:38:10Z","modified":"2026-09-10T03:50:25.994941188Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-79","CWE-94"],"updated_at":"2026-11-02T15:46:42.78452Z"},{"id":"PYSEC-2026-496","title":"pyLoad vulnerable to XSS through insecure CAPTCHA ","description":"#### Summary\nAn unsafe JavaScript evaluation vulnerability in pyLoad’s CAPTCHA processing code allows **unauthenticated remote attackers** to execute **arbitrary code** in the client browser and potentially the backend server. Exploitation requires no user interaction or authentication and can result in session hijacking, credential theft, and full system rce.\n\n\n\n#### Details\nThe vulnerable code resides in \n```javascript\nfunction onCaptchaResult(result) {\n    eval(result); // Direct execution of attacker-controlled input\n}\n```\n\n* The `onCaptchaResult()` function directly passes CAPTCHA results (sent from the user) into `eval()`\n* No sanitization or validation is performed on this input\n* A malicious CAPTCHA result can include JavaScript such as `fetch()` or `child_process.exec()` in environments using NodeJS\n * Attackers can fully hijack sessions and pivot to remote code execution on the server if the environment allows it\n\n\n\n### Reproduction Methods\n1. **Official Source Installation**:\n```bash\ngit clone https://github.com/pyload/pyload\ncd pyload\ngit checkout 0.4.20\npython -m pip install -e .\npyload --userdir=/tmp/pyload\n ```\n\n2. **Virtual Environment**:\n```bash\npython -m venv pyload-env\nsource pyload-env/bin/activate\n pip install pyload==0.4.20\npyload\n```\n\n## CAPTCHA Endpoint Verification\n\n\n **Technical Clarification**:  \n1. The vulnerable endpoint is actually:\n   ```\n   /interactive/captcha\n   ```\n\n2. Complete PoC Request:\n```http\nPOST /interactive/captcha HTTP/1.1\nHost: localhost:8000\nContent-Type: application/x-www-form-urlencoded\n \ncid=123\u0026response=1%3Balert(document.cookie)\n```\n\n3. Curl Command Correction:\n ```bash\ncurl -X POST \"http://localhost:8000/interactive/captcha\" \\\n  -d \"cid=123\u0026response=1%3Balert(document.cookie)\"\n```\n\n\n1. **Vulnerable Code Location**:  \n   The eval() vulnerability is confirmed in:\n   ```\n   src/pyload/webui/app/static/js/captcha-interactive.user.js\n   ```\n\n\n\n### **Resources**\n\n1. https://github.com/pyload/pyload/commit/909e5c97885237530d1264cfceb5555870eb9546\n 2. [OWASP: Avoid `eval()`](https://cheatsheetseries.owasp.org/cheatsheets/JavaScript_Security_Cheat_Sheet.html#eval)\n 3. [#4586](https://github.com/pyload/pyload/pull/4586)","status":"published","published":"2026-06-29T11:50:37.278367Z","modified":"2026-07-09T17:45:05.405847274Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T15:52:57.671918Z"}]}}