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CVE-2026-63345

Refitter: C# source injection through OpenAPI path keys

8.6 High

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

0.35%Unchanged since Oct 31, 2026
90%50%10%1%

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 HighCVSS: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 HighCVSS: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 HighCVSS: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 HighCVSS: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

History
RecordedChangedSources
factsEUVD, NVD, OSV
first indexedCVE 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

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