Improper Authorization and Origin Validation Error in OneFuzz
Impact
Starting with OneFuzz 2.12.0 or greater, an incomplete authorization check allows an authenticated user from any Azure Active Directory tenant to make authorized API calls to a vulnerable OneFuzz instance.
To be vulnerable, a OneFuzz deployment must be:
- Version 2.12.0 or greater
- Deployed with the non-default
--multi_tenant_domainoption
This can result in read/write access to private data such as:
- Software vulnerability and crash information
- Security testing tools
- Proprietary code and symbols
Via authorized API calls, this also enables tampering with existing data and unauthorized code execution on Azure compute resources.
Patches
This issue is resolved starting in release 2.31.0, via the addition of application-level check of the bearer token's issuer against an administrator-configured allowlist.
Workarounds
Users can restrict access to the tenant of a deployed OneFuzz instance < 2.31.0 by redeploying in the default configuration, which omits the --multi_tenant_domain option.
References
You can find an overview of the Microsoft Identity Platform here. This vulnerability applies to the multi-tenant application pattern, as described here.
For more information
If you have any questions or comments about this advisory:
- Open an issue in OneFuzz
- Email us at fuzzing@microsoft.com
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | onefuzz | >= 2.12.0, < 2.31.0 | 2.31.0 |
References
- https://github.com/microsoft/onefuzz/releases/tag/2.31.0
- https://github.com/microsoft/onefuzz/pull/1153
- https://pypi.org/project/onefuzz/
- https://github.com/microsoft/onefuzz/security/advisories/GHSA-q5vh-6whw-x745
- https://github.com/microsoft/onefuzz/commit/2fcb4998887959b4fa11894a068d689189742cb1
- https://nvd.nist.gov/vuln/detail/CVE-2021-37705
- https://github.com/microsoft/onefuzz
- https://github.com/pypa/advisory-database/tree/main/vulns/onefuzz/PYSEC-2021-344.yaml
- https://pypi.org/project/onefuzz
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L- Weakness (CWE)
CWE-285, CWE-346, CWE-863- Platform
- Python (PyPI)
- Package
onefuzz- Disclosed
- 13.08.2021
- Updated
- 11.10.2026 13:19
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2021-344 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-q5vh-6whw-x745 - CC BY 4.0
Vulnerability history: onefuzz
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
This is the only known vulnerability of this package.
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