############################################################# # # COMPASS SECURITY ADVISORY # https://www.compass-security.com/research/advisories/ # ############################################################# # # Product: Vert.x [1] # CSNC ID: CSNC-2018-021 # CVE ID: CVE-2018-12537 # Subject: HTTP Header Injection # Risk: Medium # Effect: Remotely exploitable # Author: Lukasz D. (advisories@compass-security.com) # Date: 12.06.2018 # ############################################################# Introduction: ------------- Eclipse Vert.x is a tool-kit for building reactive applications on the JVM. Vert.x can be used for simple network utilities, sophisticated modern web applications, HTTP/REST microservices, high volume event processing or a full-blown back-end message-bus applications. Vert.x is used by many different companies from real-time gaming to banking and everything in between. Vert.x does not filter carriage return and line feed characters from values of set HTTP response headers. This allows to manipulate values of the set HTTP headers and to add arbitrary new headers. In particular, issuing a redirection and manipulation of cookies set by the server is possible. Affected: --------- The following Vert.x versions are vulnerable: - 3.0.0 - 3.5.1 Technical Description: ---------------------- The method putHeader(String name, String value) used to set new headers in the HTTP response does not filter carriage return and line feed characters from the header value. If a web application uses a user-provided parameter as a value of the header, then it is possible for a user to add new HTTP headers of his choice. For example, a Vert.x-based web application may use the vulnerable method like this: putHeader("User-Header", foo), where foo is the user-provided parameter. Then: Requesting /vulnerable?foo=bar will add a header: "User-Header: bar". Requesting /vulnerable?foo=bar%0D%0ASet-Cookie:%20mycookie=hello will add a header: "User-Header: bar" and additionally will set a new cookie with name "mycookie" and value "hello". Workaround / Fix: ----------------- It needs to be ensured that every header value which is set based on a user-provided parameter does not contain carriage return and line feed characters. Timeline: --------- 2018-02-22: Vulnerability discovered 2018-04-04: Initial vendor notification 2018-04-04: Initial vendor response 2018-06-04: Patched version released 2018-06-13: Public disclosure 2018-09-14: Update assigned CVE References: ----------- [1]: https://vertx.io/