Vulnerability Instance

HAProxyMessageDecoder Stack Exhaustion DoS
### Impact
A StackOverflowError can be raised when parsing a malformed crafted message due to an infinite recursion.

### Patches
Users should upgrade to 4.1.86.Final.

### Workarounds
There is no workaround, except using a custom HaProxyMessageDecoder.

### References
When parsing a TLV with type = PP2_TYPE_SSL, the value can be again a TLV with type = PP2_TYPE_SSL and so on.
The only limitation of the recursion is that the TLV length cannot be bigger than 0xffff because it is encoded in an unsigned short type.
Providing a TLV with a nesting level that is large enough will lead to raising of a StackOverflowError.
The StackOverflowError will be caught if HAProxyMessageDecoder is used as part of Netty’s ChannelPipeline, but using it directly without the ChannelPipeline will lead to a thrown exception / crash.


### For more information
If you have any questions or comments about this advisory:
* Open an issue in [netty](https://github.com/netty/netty)