---
title: "CVE-2024-51501: CRLF injection in Refit's [Header], [HeaderCollection] and [Authorize] attributes"
url: https://erroneo.us/security/cve/CVE-2024-51501/
description: "CVE-2024-51501 (Refit (NuGet)): Refit is an automatic type-safe REST library for .NET Core, Xamarin and .NET The various header-related Refit attributes…"
type: vulnerability-record
section: "Security Digest"
date_published: 2024-11-04
date_modified: 2024-11-08
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2024-51501"
kev: false
cvss: 10
epss: 0.00562
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2024-51501: CRLF injection in Refit's [Header], [HeaderCollection] and [Authorize] attributes

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.6% , percentile 46: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 46% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes Refit (NuGet) < 7.2.22, fixed in 7.2.22 . Check your lockfile, including transitive dependencies.

## What it is

Refit is an automatic type-safe REST library for .NET Core, Xamarin and .NET The various header-related Refit attributes (Header, HeaderCollection and Authorize) are vulnerable to CRLF injection. The way HTTP headers are added to a request is via the HttpHeaders.TryAddWithoutValidation method. This method does not check for CRLF characters in the header value. This means that any headers added to a refit request 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 Refit 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 Refit and not in Refit itself. This issue has been addressed in release versions 7.2.22 and 8.0.0 and all users are advised to upgrade. There are no known workarounds for this vulnerability.

## Affected packages

- NuGet `Refit` < 7.2.22 → fixed: 7.2.22

## Affected products (CVE record)

- reactiveui refit: < 7.2.22

## Severity

- GitHub_M CVSS 4.0: 10 `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`
- GitHub CVSS 4.0: 10.0 `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable no , technical impact partial .
- FIRST EPSS (model of 2026-10-21): 0.56% probability of exploitation activity in the next 30 days; percentile 46.

## Sources

- [GitHub Advisory GHSA-3hxg-fxwm-8gf7](https://github.com/advisories/GHSA-3hxg-fxwm-8gf7)
- [CVE.org record CVE-2024-51501](https://www.cve.org/CVERecord?id=CVE-2024-51501)
- [NVD entry CVE-2024-51501](https://nvd.nist.gov/vuln/detail/CVE-2024-51501)
- [github.com](https://github.com/reactiveui/refit/security/advisories/GHSA-3hxg-fxwm-8gf7)
- [github.com](https://github.com/reactiveui/refit/blob/258a771f44417c6e48e103ac921fe4786f3c2a1e/Refit/RequestBuilderImplementation.cs#L1328)
- [github.com](https://github.com/reactiveui/refit/commit/483b1d8df18098f137ca0eca056b7e9ec19f70dd)

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Source page: https://erroneo.us/security/cve/CVE-2024-51501/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt