It seems like this was exploited on testnet (a day after being published here) in block 000000002f4830471b6b346578546615c031b99da5e7fabeac119b63f1843f82 with 5839f20446d7b9446e82c00117ee3699fa84154e970d57f09add60deef2eaa18. I tried to sync a btcd v0.23.4 node on testnet, which seems stuck on 2575398. A btcd v0.24.0 node is fine.
According to https://forkmonitor.info/nodes/btc, their mainnet btcd v0.23.3 node is still fine. I also haven’t seen a non-standard transaction exploiting this on mainnet in the past days.