CVE-2023-41900

Jetty is a Java based web server and servlet engine. Versions 9.4.21 through 9.4.51, 10.0.15, and 11.0.15 are vulnerable to weak authentication. If a Jetty OpenIdAuthenticator uses the optional nested LoginService, and that LoginService decides to revoke an already authenticated user, then the current request will still treat the user as authenticated. The authentication is then cleared from the session and subsequent requests will not be treated as authenticated. So a request on a previously authenticated session could be allowed to bypass authentication after it had been rejected by the LoginService. This impacts usages of the jetty-openid which have configured a nested LoginService and where that LoginService will is capable of rejecting previously authenticated users. Versions 9.4.52, 10.0.16, and 11.0.16 have a patch for this issue.

Jetty is a Java based web server and servlet engine. Versions 9.4.21 through 9.4.51, 10.0.15, and 11.0.15 are vulnerable to weak authentication. If a Jetty OpenIdAuthenticator uses the optional nested LoginService, and that LoginService decides to revoke an already authenticated user, then the current request will still treat the user as authenticated. The authentication is then cleared from the session and subsequent requests will not be treated as authenticated. So a request on a previously authenticated session could be allowed to bypass authentication after it had been rejected by the LoginService. This impacts usages of the jetty-openid which have configured a nested LoginService and where that LoginService will is capable of rejecting previously authenticated users. Versions 9.4.52, 10.0.16, and 11.0.16 have a patch for this issue.

From the reporter

XmlParser is vulnerable to XML external entity (XXE) vulnerability. XmlParser is being used when parsing Jetty’s xml configuration files. An attacker might exploit this vulnerability in order to achieve SSRF or cause a denial of service. One possible scenario is importing a (remote) malicious WAR into a Jetty’s server, while the WAR includes a malicious web.xml.

Impact

There are no circumstances in a normally deployed Jetty server where potentially hostile XML is given to the XmlParser class without the attacker already having arbitrary access to the server. I.e. in order to exploit XmlParser the attacker would already have the ability to deploy and execute hostile code. Specifically, Jetty has no protection against malicious web application and potentially hostile web applications should only be run on an isolated virtualisation.

Thus this is not considered a vulnerability of the Jetty server itself, as any such usage of the jetty XmlParser is equally vulnerable as a direct usage of the JVM supplied SAX parser. No CVE will be allocated to this advisory.

However, any direct usage of the XmlParser class by an application may be vulnerable. The impact would greatly depend on how the application uses XmlParser, but it could be a denial of service due to large entity expansion, or possibly the revealing local files if the XML results are accessible remotely.

Patches

Ability to configure the SAXParserFactory to fit the needs of your particular XML parser implementation have been merged as part of PR #10067

Workarounds

Don't use Jetty's XmlParser to parse data from users.

If a Jetty OpenIdAuthenticator uses the optional nested LoginService, and that LoginService decides to revoke an already authenticated user, then the current request will still treat the user as authenticated. The authentication is then cleared from the session and subsequent requests will not be treated as authenticated.

So a request on a previously authenticated session could be allowed to bypass authentication after it had been rejected by the LoginService.

Impact

This impacts usages of the jetty-openid which have configured a nested LoginService and where that LoginService will is capable of rejecting previously authenticated users.

Original Report

working on a custom OpenIdAuthenticator, I discovered the following:

https://github.com/eclipse/jetty.project/blob/jetty-10.0.14/jetty-openid/src/main/java/org/eclipse/jetty/security/openid/OpenIdAuthenticator.java#L505

In the case where the LoginService does return that the authentication has been revoked (from the validate() call on line 463), the OpenIdAuthenticator removes the authentication from the session; however the current request still proceeds as if authenticated, since it falls through to "return authentication" on line 505.

This is fixed by moving the line 505 (and associated debug log) inside the else block that ends on line 502, instead of outside it. Then the revocation case will run through to line 517 and will trigger a new OpenId authentication which I think is correct.

I think this revocation can only occur if you do attach a separate LoginService to the OpenIdLoginService, but in that case the revoked authentication will still let the next request through (and possibly more than one if they are very close to simultaneous).

Technically I think this is a security vulnerability, if a very minor one, so I'm sending this off-list.

Patched Versions

Fixed in Jetty Versions:

• 9.4.52 - fixed in PR https://github.com/eclipse/jetty.project/pull/9660
• 10.0.16 - fixed in PR https://github.com/eclipse/jetty.project/pull/9528
• 11.0.16 - fixed in PR https://github.com/eclipse/jetty.project/pull/9528
• 12.0.0 - not impacted (already has fix)

Workaround

Upgrade your version of Jetty.

References

• https://github.com/eclipse/jetty.project/pull/9528
• https://github.com/eclipse/jetty.project/pull/9660

Jetty is a Java based web server and servlet engine. Versions 9.4.21 through 9.4.51, 10.0.15, and 11.0.15 are vulnerable to weak authentication. If a Jetty OpenIdAuthenticator uses the optional nested LoginService, and that LoginService decides to revoke an already authenticated user, then the current request will still treat the user as authenticated. The authentication is then cleared from the session and subsequent requests will not be treated as authenticated. So a request on a previously authenticated session could be allowed to bypass authentication after it had been rejected by the LoginService. This impacts usages of the jetty-openid which have configured a nested LoginService and where that LoginService will is capable of rejecting previously authenticated users. Versions 9.4.52, 10.0.16, and 11.0.16 have a patch for this issue.

Jetty is a Java based web server and servlet engine. Versions 9.4.21 through 9.4.51, 10.0.15, and 11.0.15 are vulnerable to weak authentication. If a Jetty OpenIdAuthenticator uses the optional nested LoginService, and that LoginService decides to revoke an already authenticated user, then the current request will still treat the user as authenticated. The authentication is then cleared from the session and subsequent requests will not be treated as authenticated. So a request on a previously authenticated session could be allowed to bypass authentication after it had been rejected by the LoginService. This impacts usages of the jetty-openid which have configured a nested LoginService and where that LoginService will is capable of rejecting previously authenticated users. Versions 9.4.52, 10.0.16, and 11.0.16 have a patch for this issue.