Electrum patched a wallet flaw that let rogue servers steal bitcoin
Electrum disclosed that malicious servers could replace unconfirmed payments in its wallet, then sign a valid replacement sending coins to the attacker once users raised the fee. The developers reported at least one theft and released version 4.8.3, which checks signatures on unconfirmed transactions.
Only one publisher so far. Another independent outlet or an official source would raise it.
Security topic · core coin BTC
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Key facts
Attributed sources: CoinDesk
BTC after this site detected it
- 5 minutes+0.08%Gate · USDT
- 1 hour+0.07%Gate · USDT
- 24 hours—Window not complete
Claims and open questions
What sources claim
- Electrum said it received two reports in October, including one from a user who lost funds on Oct. 18 after approving a fee increase on a substituted transaction; developers have not disclosed the amount stolen.
- Before the fix, the wallet trusted outside servers to report pending transactions without checking whether their signatures were valid, and attackers also generated receiving addresses whose last four characters matched the legitimate destination.
- Electrum released version 4.8.3 on Oct. 24 adding signature checks for unconfirmed transactions, but earlier versions remain vulnerable when connected to malicious servers.
Still unresolved
- Which servers carried out the attack, and what on-chain data would identify the addresses that received the stolen coins?
- Will Electrum publish the total amount lost, and will the theft be confirmed in an official statement or filing?
Model-assisted explanation; citations, numbers and output format are checked. This is not independent semantic verification.
Source evidence
www.coindesk.com
Published 26/10/2026, 05:15 · Received 26/10/2026, 05:17
Original source titles remain in their source language. Full articles are not republished.
Market reaction after detection
Returns start at the sample closest to site detection (within the same minute up to 10 minutes later), using the same data source and quote currency. Actual sample times are shown; missing observations remain blank.
| Window | Return | Actual sampled interval / source |
|---|---|---|
| 5 minutes | +0.08% | 26/10/2026, 05:17 → 26/10/2026, 05:22 (UTC) Gate · USDT |
| 1 hour | +0.07% | 26/10/2026, 05:17 → 26/10/2026, 06:17 (UTC) Gate · USDT |
| 24 hours | — | Awaiting a complete valid window |
Historical market context
Research: hourly returns and BTC beta →
Closed hourly candles from the 30 days before this event observation. Different venues are kept separate.
| Metric | Value |
|---|---|
| Hourly coverage | 100.0% (720/720) |
| Median absolute 1h return | 0.14% |
| 99th percentile of absolute 1h returns | 1.01% |
OKX · USDT · Context as of 26/10/2026, 05:17 · Last included candle closed 26/10/2026, 05:00
Hourly descriptive statistics, not minute-move probabilities. Backfilled history never moves the observation cutoff above.
Event timeline
Source publication, receipt and analysis times are separate. All times UTC.
Source published: CoinDesk
Source received: CoinDesk
Event first detected by this site
Evidence record updated
English explanation generated
Latest content update
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