CORE LIGHTNING’S APRIL HOTFIX CITED “STRESS ON READERS” — OCTOBER 24 DISCLOSURE: ONE SIGNED MESSAGE KEPT NODES DOWN ON EVERY RESTART — FUNDS AT RISK WHILE OFFLINE

On April 25, 2026, Core Lightning shipped v26.04.1 as a hotfix. Its notes said malformed channel_announcement messages "are now rejected per BOLT spec," "preventing gossip store corruption and stress on readers." On October 24, 2026, the researcher who reported the bug, posting as NishantBansal2003, published what that line covered: Core Lightning v25.02 through v26.04 crash on an announcement that names the same node at both ends.

The node checked all four signatures and the unspent 2-of-2 output behind the channel. It never checked that the two node IDs were different. It wrote the message to disk, loaded it, tripped an internal check and shut down. On restart it read the same record and shut down again. Per the disclosure, the node stays offline "until the operator removes the record by hand," and upgrading does not remove a record already stored. The attacker's coins never leave an output it controls, so the cost is the on-chain fee.

That matters because a Lightning channel is only as safe as the node watching it. The disclosure says a node that is down "can miss a peer broadcasting a revoked commitment or an HTLC it must claim before it expires, putting funds at risk." A node that someone else can switch off from outside is a node you are trusting not to be switched off.

Here is what you can check. The fix, PR #9082, was merged April 24, 2026. The spec change, BOLT 7 PR #1333, was merged May 4, 2026 and now tells receivers to enforce the rule too. What the April notes did not tell you was that a node could stay down until a person fixed it by hand. Six months passed between the fix and that sentence. The disclosure says to run the latest release, v26.06.9. At the time of this writing, bitcoin was $80,628.