RestSharp is a Simple REST and HTTP API Client for .NET. The second argument to `RestRequest.AddHeader` (the header value) is vulnerable to CRLF injection. The same applies to `RestRequest.AddOrUpdateHeader` and `RestClient.AddDefaultHeader`. The way HTTP headers are added to a request is via the `HttpHeaders.TryAddWithoutValidation` method which does not check for CRLF characters in the header value. This means that any headers from a `RestSharp.RequestHeaders` object are added to the request in such a way that they are vulnerable to CRLF-injection. In general, CRLF-injection into a HTTP header (when using HTTP/1.1) means that one can inject additional HTTP headers or smuggle whole HTTP requests. If an application using the RestSharp library passes a user-controllable value through to a header, then that application becomes vulnerable to CRLF-injection. This is not necessarily a security issue for a command line application like the one above, but if such code were present in a web application then it becomes vulnerable to request splitting (as shown in the PoC) and thus Server Side Request Forgery. Strictly speaking this is a potential vulnerability in applications using RestSharp, not in RestSharp itself, but I would argue that at the very least there needs to be a warning about this behaviour in the RestSharp documentation. RestSharp has addressed this issue in version 112.0.0. All users are advised to upgrade. There are no known workarounds for this vulnerability.

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

  - RestSharp is a Simple REST and HTTP API Client for .NET. The second argument to `RestRequest.AddHeader`
    (the header value) is vulnerable to CRLF injection. The same applies to `RestRequest.AddOrUpdateHeader`
    and `RestClient.AddDefaultHeader`. The way HTTP headers are added to a request is via the
    `HttpHeaders.TryAddWithoutValidation` method which does not check for CRLF characters in the header value.
    This means that any headers from a `RestSharp.RequestHeaders` object are added to the request in such a
    way that they are vulnerable to CRLF-injection. In general, CRLF-injection into a HTTP header (when using
    HTTP/1.1) means that one can inject additional HTTP headers or smuggle whole HTTP requests. If an
    application using the RestSharp library passes a user-controllable value through to a header, then that
    application becomes vulnerable to CRLF-injection. This is not necessarily a security issue for a command
    line application like the one above, but if such code were present in a web application then it becomes
    vulnerable to request splitting (as shown in the PoC) and thus Server Side Request Forgery. Strictly
    speaking this is a potential vulnerability in applications using RestSharp, not in RestSharp itself, but I
    would argue that at the very least there needs to be a warning about this behaviour in the RestSharp
    documentation. RestSharp has addressed this issue in version 112.0.0. All users are advised to upgrade.
    There are no known workarounds for this vulnerability. (CVE-2024-45302)

ID	Name	Product	Family	Severity
410381	SCA: security update for RestSharp (GHSA-4rr6-2v9v-wcpc)	Tenable Cloud Security	SCA Checks	medium
410381	SCA: security update for RestSharp (GHSA-4rr6-2v9v-wcpc)	Tenable Self-Hosted Container Security	SCA Checks	medium

Detections

Analytics

CVE-2024-45302

medium

Tenable Plugins

medium

medium