Refitter: C# source injection through OpenAPI path keys
Refitter versions before 2.1.2 are affected when the OpenAPI description is attacker-controlled or attacker-influenced and its generated client is compiled into an application. Fixed in 2.1.2.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Fix
- Fixed in 2.1.2
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Refitter, a .NET tool that generates C# REST API clients from OpenAPI specifications, is affected by this vulnerability. Attacker-controlled path keys in a crafted OpenAPI document can inject arbitrary C# code into generated client files, which may then run when the generated code is compiled and loaded by an application.
Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.
Read the original description
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.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- christianhelle refitter
fixed in 2.1.2
References 7
GitHub · christianhelle/refitter
GitHub · user-attachments/files
Questions about CVE-2026-63345
What does this mean?
Refitter does not safely handle OpenAPI path keys when it generates C# source, so crafted path keys can inject C# code into the generated client. That code runs when the assembly loads at process startup in any application that compiles the client.Source: github.com
Am I affected, and how do I check?
Refitter versions before 2.1.2 are listed as affected. The exposure requires an OpenAPI description that is attacker-controlled or attacker-influenced and a generated client that is compiled into an application. Check the Refitter version used in the project's package references or tool installation.Source: github.com
What should I do about it?
Upgrade Refitter to 2.1.2 or later, the fixed version listed for this issue, and regenerate the client code.Source: github.com
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data