Tor adds defenses against directory-request floods. A proposed Monero change would exclude hidden peers from the synchronization target.
Published · Source status checked 2026-10-30. Platform guidance applies generally to public node operators.
1. Tor 0.4.9.15 adds defenses against directory-request floods
Published: October 28, 2026 · Urgency: High for public relays and bridges
Affected: Tor relays, bridges and onion-service directory traffic
Sources: Tor security release · Tor operator guidance
Tor released 0.4.9.15 with three defenses against the ongoing BEGIN_DIR flood. Per-circuit request rate limiting is enabled by default. A separate one-request-per-circuit restriction for traffic arriving from relays remains disabled pending network adoption. Onion-service directory circuits now allow only one descriptor operation. These changes limit abusive requests, but upstream warns that heavy circuit traffic can still create load.
- Linux relay operators: Upgrade relays and bridges through the normal package process. Test one instance first and confirm its version, startup logs and reachability before continuing.
- FreeBSD relay operators: Check whether the updated package is available in the repository you use. Preserve the existing configuration and package before upgrading. This advisory concerns Tor, not a monerod binary update.
- Configuration: Leave the new rate thresholds under consensus control. Do not enable DoSBeginDirLimitEnabled locally. Upstream cautions that enabling it individually could degrade the network.
- Validation and rollback: Watch CPU, memory, circuit load, consensus downloads and rejection counts in the heartbeat log. Keep a recoverable configuration backup. If rollback becomes necessary, account for losing the new flood defenses.
2. Monero proposes excluding hidden peers from the sync target
Published: October 27, 2026 · Urgency: Watch only — proposed change
Affected: monerod synchronization target calculation for Tor and I2P peers
Sources: Monero PR #11633: status and review
PR #11633 proposes excluding hidden-network peers from the target blockchain height. As checked on October 30, it has a review approval and a needs-backport label but remains open. Neither review approval nor a backport label establishes that the change is available in a release.
- FreeBSD and Linux nodes: Do not replace a production binary with this pull-request branch. Follow the merge, backport and release status before planning an upgrade for this change.
- Tor and I2P connections: If the reported target stays above the local chain, compare actual block-height progress with independent references. A displayed target alone is insufficient evidence that the local database is damaged.
- What remains uncertain: The proposal does not, by itself, establish an exploited vulnerability or a complete explanation for a stalled node. Investigate connectivity and logs before attributing a synchronization problem to this behavior.