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Fencer Intel
high 7.1

CVE-2026-63184 json

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

published 4mo ago modified 9d ago also EUVD-2026-114521 , GHSA-x6w4-f264-3vvr

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository christianhelle/refitter. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss
7.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 35%
public exploits
0
none known

Summary

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.

Patch / fix

Is CVE-2026-63184 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
9d ago

Exploit prediction

0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/christianhelle/refitter/security/advisories/GHSA-x6w4-f264-3vvr referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N

Affected products

  • christianhelle refitter

Classification

Weakness
  • CWE-829 Inclusion of Functionality from Untrusted Control Sphere
  • CWE-918 Server-Side Request Forgery

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of christianhelle/refitter published their own advisory on GitHub. Reviewed sources take precedence over it.