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A critical unauthenticated remote code execution vulnerability was found all recent versions of Apache Tapestry. The affected versions include 5.4.5, 5.5.0, 5.6.2 and 5.7.0. The vulnerability I have found is a bypass of the fix for CVE-2019-0195. Recap: Before the fix of CVE-2019-0195 it was possible to download arbitrary class files from the classpath by providing a crafted asset file URL. An attacker was able to download the file `AppModule.class` by requesting the URL `http://localhost:8080/assets/something/services/AppModule.class` which contains a HMAC secret key. The fix for that bug was a blacklist filter that checks if the URL ends with `.class`, `.properties` or `.xml`. Bypass: Unfortunately, the blacklist solution can simply be bypassed by appending a `/` at the end of the URL: `http://localhost:8080/assets/something/services/AppModule.class/` The slash is stripped after the blacklist check and the file `AppModule.class` is loaded into the response. This class usually contains the HMAC secret key which is used to sign serialized Java objects. With the knowledge of that key an attacker can sign a Java gadget chain that leads to RCE (e.g. CommonsBeanUtils1 from ysoserial). Solution for this vulnerability: * For Apache Tapestry 5.4.0 to 5.6.1, upgrade to 5.6.2 or later. * For Apache Tapestry 5.7.0, upgrade to 5.7.1 or later.\n\nFIRST-EPSS: 0.974140000\nNVD-IS: 5.9\nNVD-ES: 3.9", "creation_timestamp": "2023-11-17T07:08:00.000000Z"}, {"uuid": "868152d7-9710-4465-ab87-2edc7fc7432d", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "2a075640-a300-48a4-bb44-bc6130783b9b", "vulnerability": "CVE-2021-27850", "type": "seen", "source": "https://t.me/pwnwiki_zhchannel/712", "content": "CVE-2021-27850 Apache Tapestry\u9060\u7a0b\u57f7\u884c\u4ee3\u78bc\u6f0f\u6d1e\nhttps://www.pwnwiki.org/index.php?title=CVE-2021-27850_Apache_Tapestry%E9%81%A0%E7%A8%8B%E5%9F%B7%E8%A1%8C%E4%BB%A3%E7%A2%BC%E6%BC%8F%E6%B4%9E", "creation_timestamp": "2021-09-21T04:42:22.000000Z"}, {"uuid": "69859d12-8849-48a9-8a85-7de4a656bf85", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "2a075640-a300-48a4-bb44-bc6130783b9b", "vulnerability": "CVE-2021-27850", "type": "published-proof-of-concept", "source": "https://t.me/HackerOne/3102", "content": "CVE-2021-27850 Exploit\nhttps://github.com/kahla-sec/CVE-2021-27850_POC", "creation_timestamp": "2021-07-27T21:50:47.000000Z"}, {"uuid": "96e91f2b-f48c-4a92-bd2e-333e2b07f4da", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "2a075640-a300-48a4-bb44-bc6130783b9b", "vulnerability": "CVE-2021-27850", "type": "published-proof-of-concept", "source": "https://t.me/CyberSecurityTechnologies/3694", "content": "#exploit\nA PoC for CVE-2021-27850\naffecting Apache Tapestry and leading to unauthencticated RCE\nhttps://github.com/kahla-sec/CVE-2021-27850_POC", "creation_timestamp": "2021-06-26T13:47:51.000000Z"}, {"uuid": "1514445d-f3bc-4e6b-ac8e-d6a6d9117c28", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "2a075640-a300-48a4-bb44-bc6130783b9b", "vulnerability": "CVE-2021-27850", "type": "seen", "source": "https://t.me/CyberSecurityTechnologies/3732", "content": "#Analytics\nTop 10 Most Used Vulns of the Month (June 1-30)\nCVE-2021-1675 - Windows Print Spooler EoP\nhttps://t.me/cybersecuritytechnologies/3723\nCVE-2021-21985 - vSphere Client RCE\nhttps://t.me/cybersecuritytechnologies/3493\nCVE-2021-3560 - Privilege escalation with polkit\nhttps://t.me/cybersecuritytechnologies/3587\nCVE-2021-28476 - Hyper-V RCE in vmswitch.sys\nhttps://t.me/cybersecuritytechnologies/3514\nCVE-2020-3580 - XSS in Cisco ASA\nhttps://www.helpnetsecurity.com/2021/06/29/cve-2020-3580-exploit\nCVE-2021-31955/31956 - Windows NTFS EoP/Kernel Information Disclosure\nhttps://github.com/mavillon1/CVE-2021-31955-POC\nhttps://t.me/cybersecuritytechnologies/3705\nCVE-2021-33739 - MS DWM Core Library EoP\nhttps://t.me/cybersecuritytechnologies/3581\nCVE-2021-27850 - Apache Tapestry RCE\nhttps://t.me/cybersecuritytechnologies/3694\nCVE-2020-36289 - Atlassian Jira Unauth User Enum\nhttps://mobile.twitter.com/i/web/status/1402644004781633540", "creation_timestamp": "2021-07-01T11:03:01.000000Z"}, {"uuid": "8c88d7b1-a570-4de4-a1c4-2f9f8592d9fc", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "2a075640-a300-48a4-bb44-bc6130783b9b", "vulnerability": "CVE-2021-27850", "type": "published-proof-of-concept", "source": "https://t.me/club31337/481", "content": "https://github.com/kahla-sec/CVE-2021-27850_POC", "creation_timestamp": "2024-11-09T01:33:49.000000Z"}, {"uuid": "2724ece1-3255-42a1-a1dd-fa2144611af3", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "2a075640-a300-48a4-bb44-bc6130783b9b", "vulnerability": "CVE-2021-27850", "type": "exploited", "source": "The Shadowserver (honeypot/exploited-vulnerabilities) - 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