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TI-2026-83434 Aliases CVE-2026-63345

Code injection in Refitter C# client generator via OpenAPI path keys

Priority LOW 39CWE-1116Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Active
Attack complexity
Low
Attack requirements
None
Impact type
Code execution
Confidentiality · integrity · availability
High · High · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-94.

Summary

Refitter before 2.1.2 copies OpenAPI paths keys verbatim into Refit route attributes without escaping quotation marks (CWE-94). A remote attacker who influences the OpenAPI document can inject C# code into the generated client. A module initializer in the injected code runs when an application compiles and loads the generated assembly at startup, even if the client is never called.

Written with Claude Haiku 5.5 from the sources below · 2026-11-05

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0035 28th percentileScored 2026-11-07
Fix Fixed refitter (christianhelle): 2.1.2

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
christianhellerefitterbefore 2.1.22.1.2Patch availableCNA
  • refitter Vendorchristianhelle Affected before 2.1.2 Fixed in 2.1.2 Patch available CNA

Remediation

Upgrade Refitter to version 2.1.2.

Written with Claude Haiku 5.5 from the sources below · 2026-11-05

  • Fix · CNA refitter (christianhelle) Fixed in 2.1.2

Timeline

  1. 2026-10-30 Threatist record created from CVE-2026-63345
  2. 2026-11-01 Priority changed: MEDIUM → LOW
  3. 2026-11-02 CISA SSVC decision points changed

References

  • TI-2026-83435 Source injection in Refitter via OpenAPI header parameter names CVSS 4.0HIGH 8.6
  • TI-2026-83433 Code injection in Refitter via OpenAPI content-type map keys CVSS 4.0HIGH 8.6
  • TI-2026-83423 Refitter OpenAPI $ref handling enables SSRF and local file inclusion CVSS 3.1HIGH 7.1

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences