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

Status: published. Published: 2026-10-30. Updated: 2026-11-02.

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

No remediation reported in collected sources

## Affected products and versions

- christianhelle / refitter: < 2.1.2 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- 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; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: 0.35% as of 2026-11-02; percentile 28.69%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-94, CWE-1116

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/christianhelle/refitter/security/advisories/GHSA-3fhm-p725-h3g3 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/christianhelle/refitter/pull/1178 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/christianhelle/refitter/commit/793d2632899c2022511dfc15e30725ef69073973 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/christianhelle/refitter/releases/tag/2.1.2 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/user-attachments/files/29395228/maintainer-report.txt (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/user-attachments/files/29395229/make_spec.py (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/user-attachments/files/29395230/reproduce.sh (CNA: GitHub_M; x_refsource_MISC)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-63345; retrieved 2026-11-02; source updated 2026-11-02

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-63345; retrieved 2026-11-02; source updated Not reported

Revision: 36d69ff42f51d57044031635a53b8cfdb346036cbade84021a94e518e5ef8f79

Canonical: https://y2.dev/cve/CVE-2026-63345

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