anonhaven

CVE-2026-63344

HIGH CVSS 4.0: 8.6 EPSS 0.35%
Updated Oct 31, 2026
Christianhelle
Parameter Value
CVSS 8.6 (HIGH)
Fixed In 2.1.2
Type CWE-116 (Improper Encoding or Escaping of Output), CWE-94 (Code Injection)
Vendor Christianhelle
Public PoC No

Refitter is a tool for generating a C# REST API client using the Refit library. Prior to 2.1.2, content-type keys in the content maps of `requestBody/responses` are emitted verbatim into a Refit `[Headers("Accept: <ct>", "Content-Type: <ct>")]` attribute string without escaping quotation marks. A crafted content-type key in an attacker-influenced OpenAPI description survives default validation without `--skip-validation`, breaks out of the attribute string and enclosing interface and namespace, and can introduce a top-level file class while leaving valid generated C#.

A `[ModuleInitializer]` method in that class executes attacker code when the generated assembly is loaded at application startup, without requiring a call to the client. The behavior was verified with Refitter 2.0.0 and .NET 8. This issue is fixed in version 2.1.2.

Attack Parameters

Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
Active
User action required

Impact Assessment

Confidentiality
High
Complete data leak
Integrity
High
Complete data modification
Availability
High
Complete denial of service

CVSS Vector v4.0

Weakness Type (CWE)

CWE-116 Improper Encoding or Escaping of Output
CWE-94 Code Injection

Vulnerable Products

christianhelle:refitter

References 7

https://github.com/christianhelle/refitter/security/advisories/GHSA-p32v-8v8j-j…
https://github.com/christianhelle/refitter/security/advisories/GHSA-p32v-8v8j-j534
https://github.com/christianhelle/refitter/pull/1178
https://github.com/christianhelle/refitter/pull/1178
https://github.com/christianhelle/refitter/commit/ab4d8e439d6f0ee82ad49ee153239…
https://github.com/christianhelle/refitter/commit/ab4d8e439d6f0ee82ad49ee15323978d70fe5a67
https://github.com/christianhelle/refitter/releases/tag/2.1.2
https://github.com/christianhelle/refitter/releases/tag/2.1.2
https://github.com/user-attachments/files/29394848/reproduce.sh
https://github.com/user-attachments/files/29394848/reproduce.sh
https://github.com/user-attachments/files/29394851/maintainer-report.txt
https://github.com/user-attachments/files/29394851/maintainer-report.txt
https://github.com/user-attachments/files/29394853/make_spec.py
https://github.com/user-attachments/files/29394853/make_spec.py
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Related Vulnerabilities

CVE-2026-63346

Christianhelle

8.6