Vulnerability RUSTSEC-2026-0535

When a peer sent a PRUNE control message, the backoff it asked for was turned into an expiry time with Instant::now() + Duration::from_secs(backoff). That addition panics on overflow, so a peer that sends a PRUNE with a very large backoff, such as u64::MAX, crashes the node. No authentication is needed beyond an ordinary libp2p connection with the gossipsub protocol, and the attacker can repeat it after every restart.

The fix uses Instant::checked_add in BackoffStorage::update_backoff and ignores a backoff that would overflow. It is in 0.49.3.