Bisq v1 Trade Protocol Exploited
A modified-client attack against Bisq v1 altcoin trades; AI assistance suspected
THE EVENT
On 2026-05-01 UTC, Bisq disclosed that an attacker had exploited a missing validation check in Bisq v1's trade protocol using a modified client. A later Bisq update estimated losses at ~11 BTC, with reported affected trades limited to BTC-sell offers in XMR, ETH, and USDC pairs.
"Bisq v1 has experienced an exploit in its trade protocol that allowed an attacker to drain a portion of available offers."
— Bisq community announcement
UNAFFECTED
• Funds held in users' Bisq Bitcoin wallets were not affected by this exploit
• Bisq 2 / Bisq Easy (separate codebase and protocol design)
• Bisq 2 / Bisq Easy (separate codebase and protocol design)
AFFECTED
• Active BTC-sell offers in affected altcoin pairs
• Post-window trades requiring mediation review
• Post-window trades requiring mediation review
Was It AI-Assisted?
BISQ'S ASSESSMENT
Bisq can't say for sure, but the responding devs think AI assistance is likely — circumstantial: an AI-assisted investigation path reproduced the exploit fast after one false start.
CAVEAT
The confirmed issue is the missing validation. The attacker tooling is an inference.
Response & Reimbursement
2026-05-01 (early UTC)
Attack window begins
Attacker uses a modified Bisq v1 client against BTC sellers in affected altcoin pairs.
2026-05-01 (same day)
Trading disabled across the network
Developers triggered the emergency kill-switch, raising the required trading version to v2.0.0 (a sentinel value above any released v1 build) and halting all v1 trades immediately.
2026-05-01+
Investigation & manual code review
Developers investigate manually and with AI-assisted analysis. Users with affected post-exploit trades are told to open mediation (
Ctrl+O).Ongoing
Reimbursement options under evaluation
Current intent: reimburse in BTC, with optional BSQ. Mechanism, DAO approval, and timing are still being worked out.
Containment
CONTAINMENT ACTIONS
• Trading stopped via the forced-version mechanism.
• Current theory published: negative taker-provided miner fee, 0.001 BTC multisig output, and taker change output.
• Bisq 2 unaffected (separate codebase and protocol).
• Current theory published: negative taker-provided miner fee, 0.001 BTC multisig output, and taker change output.
• Bisq 2 unaffected (separate codebase and protocol).