{"id":"CMP-202611-o62s3g","kind":"campaign","aliases":[],"related":[],"title":"Mercado Bitcoin, Brazil's largest crypto exchange, breached: about $46M drained from its wallets, deposits and withdrawals halted","description":null,"summary":"Mercado Bitcoin confirmed on 2 Nov 2026 that attackers got into 'one of our systems' early that morning and moved about $46.3M in crypto (Arkham data). Arkham says the attacker swept funds from older deposit addresses and is selling memecoins and altcoins. Tether froze more than 4.5M USDT linked to the attacker. The exchange paused deposits and withdrawals and says customers' funds and data were not affected. How the attackers got in and who they are: unknown. This is the latest in a run of crypto platform breaches (Binance, Polymarket, Chainalysis).","severity":"high","cvss":null,"epss":null,"exploited":true,"exploited_at":"2026-11-02T23:06:02+00:00","products":[{"name":"Mercado Bitcoin","fixed":[],"vendor":"Mercado Bitcoin"}],"ecosystems":[],"tags":["campaign","early-warning"],"not_affected_if":[],"how_to_check":"Check whether your organisation or treasury holds funds at Mercado Bitcoin or has pending deposits or withdrawals there. Check whether your wallets received funds from the destination addresses Mercado Bitcoin posted on X; the addresses are not in our sources. The way in is unknown, so there are no indicators for your own systems yet.","fix":"Do not send new deposits to Mercado Bitcoin deposit addresses until the exchange says it is safe. Watch its official X account for when withdrawals resume and for its findings. If you received funds from the flagged addresses, freeze them and report them to the exchange.","status":"open","published_at":null,"first_seen_at":"2026-11-02T23:06:02+00:00","triaged_at":"2026-11-02T23:06:02+00:00","updated_at":"2026-11-02T23:06:02+00:00","category":"vendor","confidence":null,"triage":null,"analyst_status":"done","analyst_note":null,"search":"'-202611':20A '2':32B '2026':34B '4.5':75B '46.3':49B '46m':10A 'address':64B 'affect':96B 'altcoin':70B 'arkham':53B,55B 'attack':36B,58B,81B,99B 'binanc':118B 'bitcoin':2A,23A,29B 'brazil':3A 'breach':8A,117B 'campaign':24B 'chainalysi':120B 'cmp':19A 'confirm':30B 'crypto':6A,52B,115B 'custom':90B 'data':54B,93B 'deposit':15A,63B,85B 'drain':11A 'earli':26B,43B 'early-warn':25B 'exchang':7A,83B 'froze':72B 'fund':60B,91B 'got':37B,100B 'halt':18A 'largest':5A 'latest':110B 'link':78B 'm':50B,76B 'memecoin':68B 'mercado':1A,22A,28B 'morn':45B 'move':47B 'nov':33B 'o62s3g':21A 'older':62B 'one':39B 'paus':84B 'platform':116B 'polymarket':119B 'run':113B 'say':56B,89B 'sell':67B 'swept':59B 'system':42B 'tether':71B 'unknown':106B 'usdt':77B 'wallet':14A 'warn':27B 'withdraw':17A,87B","nicknames":[],"mitigations":[],"who_affected":null,"tier":"A","verified":{},"analyst_revisit_at":null,"fix_status":null,"audience":null,"plain_action":null,"pkeys":["bitcoin","mercadobitcoin"],"ptokens":["bitcoin","mercado"],"labels":["campaign","earlywarning","high","vendor"],"first_public_at":"2026-11-02T20:19:49+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"analyst","external_id":"CMP-202611-o62s3g","url":null,"severity":null,"published_at":null,"modified_at":null,"first_seen_at":"2026-11-02T23:06:02+00:00","fetched_at":"2026-11-02T23:06:02+00:00","note":null}],"documents":[{"id":54281,"url":"https://bsky.app/profile/techmeme.com/post/3mzefxyhij52f","title":"@techmeme.com: Brazil's largest crypto exchange Mercado Bitcoin halts withdrawals after a breac","kind":"post","source":"bluesky","publisher":null,"text":"Brazil's largest crypto exchange Mercado Bitcoin halts withdrawals after a breach involving $46.4M in assets, per Arkham; Tether froze 4.5M+ USDT in response (Jason Shubnell/The Block)\n\nMain Link | Techmeme Permalink\nhttps://www.theblock.co/news/defi/2026-11-02-mercado-bitcoin-hack-46-million-brazil-exchange-432333 http://www.techmeme.com/261102/p43#a261102p43\n\nlikes 0 reposts 2","published_at":"2026-11-02T22:51:18+00:00","relation":"describes","confidence":null,"note":null},{"id":54312,"url":"https://www.theblock.co/news/defi/2026-11-02-mercado-bitcoin-hack-46-million-brazil-exchange-432333","title":"Mercado Bitcoin, Brazil's largest crypto exchange, hit by $46 million security breach","kind":"other","source":"analyst","publisher":null,"text":"Mercado Bitcoin confirmed Monday 2 Nov 2026 a security incident involving about $46.3M in assets (Arkham data). Exchange: 'We identified and swiftly contained a security incident in one of our systems early this morning.' Deposits and withdrawals suspended. Exchange says customers not affected and no data breach; published destination wallet addresses on X. Tether CEO Paolo Ardoino confirmed freeze of 4.5M+ USDT linked to the incident. Arkham analyst Emmett Gallic: attacker sweeping funds from older deposit addresses and selling memecoins and altcoins. Comes after Binance $6B hack, Polymarket $2.65M third-party provider exploit, Chainalysis breach, Name.com DeFi site hijacks.","published_at":"2026-11-02T20:19:49+00:00","relation":"describes","confidence":null,"note":null}],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}