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.

There are packages installed that are affected by a vulnerability referenced in the following CVE:

  - 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. (CVE-2021-27850)

Apache Tapestry versions 5.4.0 < 5.6.2 and 5.7.0 < 5.7.1 allows an unauthenticated attacker to access Class files via a specially crafted request. If the value of 'tapestry.hmac-passphrase' is recovered, this vulnerability can be exploited to obtain arbitrary code execution through the value of the 't:formdata' parameter when a form is sent.

ID	Name	Product	Family	Severity
416998	SCA: security update for org.apache.tapestry:tapestry-core (GHSA-mj8x-cpr8-x39h)	Tenable Cloud Security	SCA Checks	critical
416998	SCA: security update for org.apache.tapestry:tapestry-core (GHSA-mj8x-cpr8-x39h)	Tenable Self-Hosted Container Security	SCA Checks	critical
114448	Apache Tapestry Arbitrary File Read	Web App Scanning	Component Vulnerability	critical

Detections

Analytics

CVE-2021-27850

critical

Tenable Plugins

critical

critical

critical