---
id: CVE-2026-63345
title: 'Refitter: C# source injection through OpenAPI path keys'
summary: >-
  Refitter is a tool for generating a C# REST API client using the Refit
  library. Prior to 2.1.2, OpenAPI `paths`-object keys are emitted verbatim into
  Refit route attributes such as `[Get("<path>")]` without escaping quotation
  marks or re…
severity: high
cvss: 8.6
cvssVector: 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'
cvssSource: cna
cwe:
  - CWE-94
  - CWE-1116
vendor: christianhelle
product: refitter
affected:
  - refitter < 2.1.2
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: total
  timestamp: '2026-11-02T17:09:18.405090Z'
published: '2026-10-30'
updated: '2026-11-02'
sourceUpdated: '2026-11-02T17:58:04.730Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-63345'
references:
  - url: >-
      https://github.com/christianhelle/refitter/security/advisories/GHSA-3fhm-p725-h3g3
    label: >-
      https://github.com/christianhelle/refitter/security/advisories/GHSA-3fhm-p725-h3g3
  - url: 'https://github.com/christianhelle/refitter/pull/1178'
    label: 'https://github.com/christianhelle/refitter/pull/1178'
  - url: >-
      https://github.com/christianhelle/refitter/commit/793d2632899c2022511dfc15e30725ef69073973
    label: >-
      https://github.com/christianhelle/refitter/commit/793d2632899c2022511dfc15e30725ef69073973
  - url: 'https://github.com/christianhelle/refitter/releases/tag/2.1.2'
    label: 'https://github.com/christianhelle/refitter/releases/tag/2.1.2'
  - url: 'https://github.com/user-attachments/files/29395228/maintainer-report.txt'
    label: 'https://github.com/user-attachments/files/29395228/maintainer-report.txt'
  - url: 'https://github.com/user-attachments/files/29395229/make_spec.py'
    label: 'https://github.com/user-attachments/files/29395229/make_spec.py'
  - url: 'https://github.com/user-attachments/files/29395230/reproduce.sh'
    label: 'https://github.com/user-attachments/files/29395230/reproduce.sh'
tags:
  - cve.org
epss: 0.0035
epssPercentile: 0.28833
ingestedAt: '2026-11-05T19:30:42.760Z'
---

## Overview

Refitter is a tool for generating a C# REST API client using the Refit library. Prior to 2.1.2, OpenAPI `paths`-object keys are emitted verbatim into Refit route attributes such as `[Get("<path>")]` without escaping quotation marks or restricting characters. An attacker-influenced single-line, slash-prefixed path survives default validation without `--skip-validation` and can close the attribute string, interface, and namespace while introducing a top-level file class and reopening the generated structure to keep valid C#. A `[ModuleInitializer]` method executes attacker code when an application compiles and loads the generated assembly at startup, even without calling the generated client. The enum and default value sinks are escaped and are not the vulnerable path-emission sink. The behavior was verified on Refitter 2.0.0 with .NET 8. This issue is fixed in version 2.1.2.

## Affected

- `refitter < 2.1.2`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.