Do BIP199's HTLCs suffer from script malleability?

Question

Do BIP199 HTLCs suffer from sigscript malleability like multisigs do due to OP_CHECKMULTISIG?

Answer 1

The Script define in bip-0199 may suffer from OP_IF malleability if not used in a witness Script (which enforces that the argument to OP_IF is minimal, that is either the empty vector or 0x01).

There may be other malleability sources in this Script that i didn't spot, and more generally malleability being very difficult to reason about it's worth using tools such as Miniscript to prevent your Script's satisfaction(s) to be (too much) malleable.