本问题的解决方案是使用golang的crypto/aes包。通过将密文解码为字节数组，将其传递给cipher.NewCBCDecrypter并使用给定的密钥和初始向量对其进行解密。最后，我们使用PKCS7填充机制去掉填充。

package main

import (
	"bytes"
	"crypto/aes"
	"crypto/cipher"
	"errors"
)

func main() {
	key := []byte("0123456789abcdef")
	iv := []byte("abcdef0123456789")

	ciphertext := []byte{0x6e, 0x9e, 0xc0, 0x1f, 0x25, 0x90, 0xee, 0x40, 0x2d, 0xb2, 0xa9, 0x39, 0xac, 0xa3, 0x3a, 0x67}

	plaintext, err := aesCBCDecrypt(key, iv, ciphertext)
	if err != nil {
		panic(err)
	}

	println(string(plaintext))
}

func aesCBCDecrypt(key, iv, ciphertext []byte) ([]byte, error) {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}

	if len(ciphertext)%aes.BlockSize != 0 {
		return nil, errors.New("ciphertext is not a multiple of the block size")
	}

	mode := cipher.NewCBCDecrypter(block, iv)

	mode.CryptBlocks(ciphertext, ciphertext)

	return pkcs7Unpad(ciphertext), nil
}

func pkcs7Unpad(data []byte) []byte {
	length := len(data)
	unpadding := int(data[length-1])
	return data[:(length - unpadding)]
}