Bug 2010164 (CVE-2021-3856)

Summary: CVE-2021-3856 keycloak-services: ClassLoaderTheme and ClasspathThemeResourceProviderFactory allows reading any file available as a resource to the classloader
Product: [Other] Security Response Reporter: Paramvir jindal <pjindal>
Component: vulnerabilityAssignee: Nobody <nobody>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: aschwart, aszczucz, boliveir, chazlett, drichtar, jochrist, jwon, mposolda, pdrozd, pjindal, rgodfrey, rmartinc, ssilvert, sthorger, vmuzikar
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 2009712, 2010282    

Description Paramvir jindal 2021-10-04 05:21:20 UTC 
https://issues.redhat.com/browse/KEYCLOAK-19422

https://github.com/keycloak/keycloak/blob/master/services/src/main/java/org/keycloak/theme/ClasspathThemeResourceProviderFactory.java

The ThemeResource resource exposes an endpoint for fetching theme resources:

@GET
@Path("/{version}/{themeType}/{themeName}/{path:.*}")
public Response getResource(@PathParam("version") String version, @PathParam("themeType") String themType, @PathParam("themeName") String themeName, @PathParam("path") String path) {
...
}

The classbased resource loaders are implemented as:

public InputStream getResourceAsStream(String path) {
    return classLoader.getResourceAsStream(resourceRoot + path);
}

This has no checks for the path parameter, allowing relative traversals like ../.

By sending requests for theme resources with a relative path from an external HTTP client, the client will receive the content of random files if available.

I practice this exposes any files packages within the deployed module, including other resources available as a classloader resource.

Disallowing double dots in the path component is probably the easiest fix
Comment 2 Jonathan Christison 2021-10-04 17:43:36 UTC 
This vulnerability is out of security support scope for the following products:
 
* Red Hat AMQ Online 

Please refer to https://access.redhat.com/support/policy/updates/jboss_notes and https://access.redhat.com/solutions/5941551 for more details.