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Vulnerability · Published Oct 30, 2026 · Assigned by GitHub_M

CVE-2026-63344Refitter: C# source injection through OpenAPI content-type map keys

High 8.6

In plain English

A high-severity code injection in refitter from christianhelle. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 29% of all known vulnerabilities).

Severity (CVSS 4.0)8.6High
Exploit odds (30 days)0.4%top 71.2% of all CVEs
Exploited in the wildNo reportsnot in CISA KEV
Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

VendorProductVersions
christianhelle refitter < 2.1.2

Weakness: CWE-94, CWE-116 · Vector: 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

References