LND Validation Barrier Map Leak via ChannelAnnouncement Spam

Impact

Any peer, with no prior channel relationship, could exhaust a victim lnd node’s memory by spamming channel_announcement messages. The gossiper’s validation barrier initializes internal dependency maps (nodeAnnDependencies, chanEdgeDependencies) for each incoming announcement but failed to clean those maps up after processing. An attacker that sends a continuous stream of channel_announcement messages fills the maps without bound, eventually OOM-killing the process.

There is no fund-loss path. The node restarts cleanly once the attacker disconnects, but the attack can be repeated.

Severity

Scored against the Lightning Labs severity taxonomy (4-dimension rubric):

Dimension	Score	Reasoning
Impact	Low	OOM crash. The node restarts cleanly when the attacker disconnects; no fund-loss path and no sustained liveness invalidation.
Attack Vector	High	Network. Any peer can send channel_announcement messages with no prior channel relationship.
Exploitability	High	Trivially executable; a continuous stream of announcements saturates the maps on a default configuration.
Virality	Low	Per-victim. The attacker must hold a connection to each target; the attack does not propagate through the network.

Result: T3. Rule 3 (Impact = Low, base T3); no promotion because Virality is not High. A reachable non-viral crash-DoS is T3 regardless of how trivially it triggers.

Patches

The issue was fixed in lnd v0.19.0-beta. Users should update to v0.19.0-beta or later to be protected.

Disclosure timeline

• Identified internally by the Lightning Labs security team.
• Fix merged and released in lnd v0.19.0-beta.
• Public disclosure: 2026-08-11.