Coinjoin Research Exposes Privacy Weaknesses Across Several Bitcoin Wallets
Bitcoin privacy research showed how a malicious or compromised coordinator could undermine anonymity assumptions in several centralized coinjoin implementations. The findings affected current or former versions of wallets including Wasabi, Ginger, Samourai, Sparrow and Trezor Suite.
Bitcoin Optech summarized research from Yuval Kogman examining centralized coinjoin protocols and showing how a coordinator could potentially learn more about participant input-output relationships than users expected. The issue was not that coinjoin cryptography had simply failed; rather, the design and coordination model created opportunities for metadata correlation and active attacks.
The research was relevant across several major Bitcoin privacy tools and current or former wallet implementations, including Wasabi, Ginger, Samourai, Sparrow and Trezor Suite. Because many users had relied on coinjoin specifically to reduce transaction graph linkability, weaknesses at the coordinator layer carried direct practical consequences for privacy assumptions.
The January publication is historically important because it illustrates a recurring Bitcoin privacy lesson: privacy systems can fail at the protocol-orchestration and metadata layers even when signatures and transaction validity remain intact. The episode also contributed to a broader reassessment of centralized coinjoin architectures.