Is CVE-2026-63346 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-63346 being exploited in the wild.

How severe is CVE-2026-63346?

Informational severity, published 30 October 2026.

Which products and versions are affected?

Christian Helle Refitter prior to 2.1.2.

How is CVE-2026-63346 attacked?

It is attacked over the network, in a software library.

Am I affected by CVE-2026-63346?

Check whether you run Christian Helle Refitter at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-63346: Refitter C# REST client generator code injection in header attribute

CVE-2026-63346 · Severity: info · Published 2026-10-30

Refitter is a code generator that creates C# REST API clients from OpenAPI descriptions. A flaw in header parameter name handling allows an attacker to inject malicious C# code into generated source files through a crafted OpenAPI specification, achieving remote code execution when the compiled assembly loads at application startup without requiring the client to be called.

Technologies: Christian Helle Refitter. Vendors: Christian Helle.

Quick answers

Is CVE-2026-63346 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-63346 being exploited in the wild.
How severe is CVE-2026-63346?: Informational severity, published 30 October 2026.
Which products and versions are affected?: Christian Helle Refitter prior to 2.1.2.
Is there a fix for CVE-2026-63346?: Yes: fixed in 2.1.2. Until then: Upgrade to version 2.1.2 or later. If upgrading is not immediately possible, avoid using Refitter to generate clients from untrusted or externally-sourced OpenAPI specifications. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-63346 attacked?: It is attacked over the network, in a software library.
Am I affected by CVE-2026-63346?: Check whether you run Christian Helle Refitter at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

Fixed in: 2.1.2

Upgrade to version 2.1.2 or later. If upgrading is not immediately possible, avoid using Refitter to generate clients from untrusted or externally-sourced OpenAPI specifications.

Technical details

The vulnerability is an attribute string injection flaw in HeaderParameterExtractor where header parameter names from OpenAPI specifications are emitted verbatim into Refit `[Header("...")]` attributes without escaping quotation marks. An attacker can craft an OpenAPI description that breaks out of the attribute string, closes the interface and namespace, and injects a top-level C# class with a `[ModuleInitializer]` method, achieving code execution at assembly load. The generated code remains valid C# and compiles successfully. This is fixed in version 2.1.2 by escaping special characters in header parameter names.

Affected products

Christian Helle Refitter prior to 2.1.2

Timeline

2026-10-30: disclosed: CVE-2026-63346 published
2026-07-27: patched: Fix merged in version 2.1.2

References

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