Security of very simple XOR with random?
Your cipher is a synchronous stream cipher build on a random number generator.

For cryptographically secure random number generators (CSRNG), this is a secure stream cipher.

The problem is, that your random seed is way too small for any security. Trying all possible seeds and seeing if the decryption result makes some sense (assuming the plaintext makes sense) is possible in some seconds, I guess, even with non-specialized hardware.

Also, the random number generator used by your program is quite likely not a CSRNG (otherwise it would not have a 32-bit seed), so there might even be other ways to attack it.

Also, as you don't have any initialization vector, you have the usual stream cipher problem: As soon as you reuse a key twice, you have the same keystream twice. Then the attacker can XOR both ciphertexts and get $c_1 \oplus c_2 = (p_1 \oplus k) \oplus (p_2 \oplus k) = p_1 \oplus p_2$ – and from this we often can extract parts of the plaintexts, especially if these are longer messages.