Versions of the package fastecdsa before 2.3.2 are vulnerable to Use of Uninitialized Variable on the stack, via the curvemath_mul function in src/curveMath.c, due to being used and interpreted as user-defined type. Depending on the variable's actual value it could be arbitrary free(), arbitrary realloc(), null pointer dereference and other. Since the stack can be controlled by the attacker, the vulnerability could be used to corrupt allocator structure, leading to possible heap exploitation. The attacker could cause denial of service by exploiting this vulnerability.
https://security.snyk.io/vuln/SNYK-PYTHON-FASTECDSA-6262045
https://github.com/AntonKueltz/fastecdsa/commit/57fc5689c95d649dab7ef60cc99ac64589f01e36
https://github.com/AntonKueltz/fastecdsa/blob/v2.3.1/src/curveMath.c%23L210
https://gist.github.com/keltecc/49da037072276f21b005a8337c15db26