CVE-2026-63184

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CVE-2026-63184

Summary: Refitter: Unrestricted OpenAPI references permit build-host SSRF and file inclusion

Details: Refitter is a tool for generating a C# REST API client using the Refit library. Prior to 2.1.1, the `refitter` dotnet tool invokes `NJsonSchema` with unsafe defaults for `$ref` resolution when generating Refit interfaces and contracts from attacker-controlled or attacker-influenced OpenAPI descriptions. Remote `http(s)` references cause requests from the developer or CI host and inline untrusted remote schema content into generated output. Absolute local file paths and relative `../` traversal outside the input directory also resolve and inline local content, permitting arbitrary local-file disclosure. The demonstrated chain stops at server-side request forgery, remote file inclusion, and local file inclusion, not code execution: Refit sets the base URL at runtime, enum values use verbatim-string doubling, and string defaults are escaped. This issue is fixed in version 2.1.1.

References: https://github.com/christianhelle/refitter/releases/tag/2.1.1, https://github.com/user-attachments/files/29395269/reproduce.sh, https://github.com/user-attachments/files/29395271/maintainer-report.txt, https://github.com/user-attachments/files/29395283/reproduce.sh, https://github.com/user-attachments/files/29395284/maintainer-report.txt, https://github.com/user-attachments/files/29395286/listener.py, https://github.com/user-attachments/files/29395288/make_spec.py, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/63xxx/CVE-2026-63184.json, https://github.com/christianhelle/refitter/security/advisories/GHSA-x6w4-f264-3vvr, https://github.com/user-attachments/files/29395272/advisory.md, https://github.com/user-attachments/files/29395285/advisory.md, https://nvd.nist.gov/vuln/detail/CVE-2026-63184, https://github.com/christianhelle/refitter/commit/6ad20a3803561225100b0a4bb6b12f947d23db7b, https://github.com/christianhelle/refitter/pull/1173