Impact

Panic vulnerability when a specially crafted payload is used.
This is because of the following calculation:

inner_payload_len + (4 - inner_payload_len % 4) % 4

If inner_payload_len is 0xffffffff, (4 - inner_payload_len % 4) % 4 = 1 so

inner_payload_len + (4 - inner_payload_len % 4) % 4 = u32::MAX + 1

which overflow.

Patches

Check that inner_payload_len is not above 64 which should never be the case.
Patched in version 0.0.8

Workarounds

Sanitize input payload before it is passed to the vulnerable function so that bytes in payload[32..32+4] and parsed as a u32 is not above 64.

References

GitHub issue #58