CVE-2021-27850 – org.apache.tapestry:tapestry-core

Package

Manager: maven
Name: org.apache.tapestry:tapestry-core
Vulnerable Version: >=5.4.0 <5.6.3 || >=5.7.0 <5.7.1

Severity

Level: Critical

CVSS v3.1: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N/E:P/RL:O/RC:C

CVSS v4.0: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N

EPSS: 0.94219 pctl0.99917

Details

Remote code execution in Apache Tapestry 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 5.6.2, upgrade to 5.6.3 or later. * For Apache Tapestry 5.7.0, upgrade to 5.7.1 or later.

Metadata

Created: 2021-06-16T17:33:19Z
Modified: 2021-04-19T21:38:56Z
Source: https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2021/06/GHSA-mj8x-cpr8-x39h/GHSA-mj8x-cpr8-x39h.json
CWE IDs: ["CWE-502", "CWE-922"]
Alternative ID: GHSA-mj8x-cpr8-x39h
Finding: F096
Auto approve: 1