CVE-2026-63346
Refitter: C# source injection through OpenAPI header parameter names
Refitter is a tool for generating a C# REST API client using the Refit library. Prior to 2.1.2, the header parameter name in `parameters[].name` with `in: header` is emitted verbatim into a Refit `[Header("<name>")]` attribute string without escaping quotation marks. An attacker-influenced OpenAPI description can pass default validation without `--skip-validation` and break out from the parameter-list position by closing the parameter and method syntax, attribute, interface, and namespace. The generated file can remain valid C# while containing a top-level file class with a `[ModuleInitializer]` method, which executes attacker code when the compiled assembly is loaded at application startup, even if the client is never called. Query `AliasAs` and enum/default value sinks are escaped; this flaw is in header-name attribute-string emission. The behavior was verified with Refitter 2.0.0 and .NET 8. This issue is fixed in version 2.1.2.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| refitter christianhelle |
< 2.1.2 (affected) | CNA: GitHub_M |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 8.6 high |
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 | CNA: GitHub_M |
Exploit evidence
- https://github.com/christianhelle/refitter/security/advisories/GHSA-58x9-vjvp-6mx8
exploit · ADP: CISA-ADP
References
- https://github.com/christianhelle/refitter/security/advisories/GHSA-58x9-vjvp-6mx8CNA: GitHub_M · x_refsource_CONFIRM
- https://github.com/christianhelle/refitter/pull/1178CNA: GitHub_M · x_refsource_MISC
- https://github.com/christianhelle/refitter/commit/63a19b03699a9c267d6fab5f758ec26484db83a1CNA: GitHub_M · x_refsource_MISC
- https://github.com/christianhelle/refitter/releases/tag/2.1.2CNA: GitHub_M · x_refsource_MISC
- https://github.com/user-attachments/files/29395048/maintainer-report.txtCNA: GitHub_M · x_refsource_MISC
- https://github.com/user-attachments/files/29395050/make_spec.pyCNA: GitHub_M · x_refsource_MISC
- https://github.com/user-attachments/files/29395051/reproduce.shCNA: GitHub_M · x_refsource_MISC
- https://github.com/christianhelle/refitter/security/advisories/GHSA-58x9-vjvp-6mx8ADP: CISA-ADP · exploit
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