GHSA-f5cx-h789-j959 PowSyBl Core allows deserialization of untrusted SparseMatrix data

• Maven com.powsybl:powsybl-math: >= 6.3.0, < 6.7.2 → fixed in 6.7.2

Impact _What kind of vulnerability is it? Who is impacted?_ This is a disclosure for a security vulnerability in the `SparseMatrix` class. The vulnerability is a deserialization issue that can lead to a wide range of privilege escalations depending on the circumstances. The problematic area is the `read` method of the `SparseMatrix` class. This method takes in an `InputStream` and returns a `SparseMatrix` object. We consider this to be a method that can be exposed to untrusted input in at least two use cases: • A user can adopt this method in an application where users can submit an `InputStream` and the application parses it into a `SparseMatrix`. This can be a multi-tenant application that hosts many different users perhaps with different privilege levels. • A user adopts the method for a local tool but receives the `InputStream` from external sources. Am I impacted? You are vulnerable if you import non-controlled serialized `SparseMatrix` objects. Patches com.powsybl:powsybl-math:6.7.2 and higher Workarounds _Is there a way for users to fix or remediate the vulnerability without upgrading?_ Do not use `SparseMatrix` deserialization (`SparseMatrix.read(...)` methods). References powsybl-core v6.7.2