CVE-2026-63345
Refitter: C# source injection through OpenAPI path keys
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- Active
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
8.6
Refitter: C# source injection through OpenAPI path keys
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.
- Record
CVE-2026-63345- CVSS 4.0
- 8.6 High
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 - Weakness
- CWE-94, CWE-1116
- Updated
- 2026-11-02
EUVDEUVD-2026-114538
8.6
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.
- Record
EUVD-2026-114538- CVSS 4.0
- 8.6 High
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 - Updated
- 2026-11-03
NVD
8.6
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.
- Record
CVE-2026-63345- CVSS 4.0
- 8.6 High
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - Weakness
- CWE-94, CWE-1116
- Updated
- 2026-11-03
OSV
8.6
Refitter: C# source injection through OpenAPI path keys
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.
- Record
CVE-2026-63345- CVSS 4.0
- 8.6 High
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 - Weakness
- CWE-1116, CWE-94
- Updated
- 2026-11-04
Affected products
History
| Recorded | Changed | Sources |
|---|---|---|
| facts | EUVD, NVD, OSV | |
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-63345 is a high vulnerability (CVSS 8.6) in Christianhelle Refitter, published October 30, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.35%, the 28th percentile. No source names a fixed version.
References
github.com/christianhelle/refitter/security/advisories/GHSA-3fhm-p725-h3g3
github.com/christianhelle/refitter/pull/1178
github.com/christianhelle/refitter/commit/793d2632899c2022511dfc15e30725ef69073973
github.com/christianhelle/refitter/releases/tag/2.1.2
github.com/user-attachments/files/29395228/maintainer-report.txt
github.com/user-attachments/files/29395229/make_spec.py
github.com/user-attachments/files/29395230/reproduce.sh
github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63345.json
nvd.nist.gov/vuln/detail/CVE-2026-63345