Although code using a specific program language may not be susceptible to a buffer overflow attack,

Plug-in susceptibility is a separate attack surface concern and is not the primary technical reason why memory-safe language code can still be indirectly vulnerable; the question targets the foundational execution environment.

While supporting application code could theoretically be vulnerable, this is not the specific and well-established security concern that directly undermines the memory safety guarantees provided by managed languages.

Graphical images can be vectors for exploits (e.g., malformed image parsing), but this is an application-layer parsing vulnerability, not the core reason why a memory-safe language's broader execution environment remains at risk.

Languages like Java and C# are memory-safe and abstract away direct memory management, making application-level buffer overflows largely impossible. However, the virtual machine (e.g., the JVM or CLR) that interprets or JIT-compiles the bytecode is itself written in native code (typically C/C++), which is susceptible to buffer overflow vulnerabilities. A flaw in the VM's own code can be exploited even though the application layer is safe, meaning the security of the entire stack depends on the VM's integrity.