CVE-2026-63345: Refitter: C# source injection through OpenAPI path keys

Published Oct 30, 2026
·
Updated

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.

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade Refitter to a version that resolves this vulnerability.

    Fixed in 2.1.2

Event History

Oct 30, 2026
CVE Published
via MITRE·10:13 PM
Data Sourced
via MITRE·10:13 PM
DescriptionWeakness
Data Sourced
via OSV·10:13 PM
DescriptionSeverityWeakness
Data Sourced
via NVD·11:17 PM
DescriptionSeverityWeakness

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