OSSA-2026-040: Multiple authorization vulnerabilities in the Blazar V2 lease API

Date:

September 21, 2026

CVE:

CVE-2026-93852, CVE-2026-93854

Affects

  • Blazar: >=1.0.0 <15.1.1, ==16.0.0, ==17.0.0

Description

Rohan Das from the University of Engineering and Management, Kolkata, reported that the Blazar V2 lease API does not enforce object-level authorization on its update and delete operations. As a result, any authenticated user who knows a lease ID can modify or delete leases belonging to other users and projects.

The same reporter found that the Blazar V2 lease listing operation returns leases for every project without enforcing project scoping or an administrator-only policy. Any authenticated user can enumerate other projects’ leases, exposing lease and reservation identifiers along with reservation metadata. The exposed identifiers enable the object-level authorization bypass described above, allowing an attacker to then modify or delete the enumerated leases.

Only deployments that enable Blazar’s V2 lease API are affected. Deployers that do not use the V2 API endpoint can set api_v2_controllers to an empty value in the [api] section of blazar.conf. Patches below address the issue if the API controllers cannot be disabled.

Patches

Credits

  • Rohan Das from University of Engineering and Management, Kolkata

References

Notes

  • A single patch on each branch fixes both vulnerabilities.