We have a message (the flag) encrypted with the same $N$, but with two different $e$.
As the name suggests the solution to this problem is a [common modulus attack](https://crypto.stackexchange.com/questions/16283/how-to-use-common-modulus-attack)

[...]

```python
from binascii import unhexlify
def solve(e1, e2, n, c1, c2):
d, x, y = xgcd(e1, e2)
m = (pow(c1, x, n) * pow(c2, y, n)) % n
print unhexlify(hex(long(m))[2:-1])
```

for the original writeup check out [https://theromanxpl0it.github.io/ctf_codeblue2017/common1](https://theromanxpl0it.github.io/ctf_codeblue2017/common1/)

Original writeup (https://theromanxpl0it.github.io/ctf_codeblue2017/common1/).