Small crypto-miners can now pull off a 'Temporary PAW' attack to steal 22x more rewards than previously possible.
April 16, 2026
Original Paper
Temporary Power Adjusting Withholding Attack
arXiv · 2604.14135
The Takeaway
Mining pools rely on the honesty of small contributors, but this new attack shows how easy it is to break that trust. By strategically withholding blocks, even small-scale miners can dramatically increase their earnings at the expense of the pool. The 22x increase in reward efficiency over previous attacks makes this a credible threat to the stability of decentralized mining. It reveals a structural vulnerability in how Bitcoin-style pools calculate contributions. For blockchain engineers, this means current pool reward mechanisms are fundamentally broken and require a complete redesign to survive incentivized adversaries. It turns a niche security concern into a major systemic risk.
From the abstract
We consider the block withholding attacks on pools, more specifically the state-of-the-art Power Adjusting Withholding (PAW) attack. We propose a generalization called Temporary PAW (T-PAW) where the adversary withholds a fPoW from pool mining at most $T$-time even when no other block is mined. We show that PAW attack corresponds to $T\to\infty$ and is not optimal. In fact, the extra reward of T-PAW compared to PAW improves by an unbounded factor as adversarial hash fraction $\alpha$, pool size