XRP Ledger's payment engine contained an integer overflow vulnerability dating to 2015 that could have enabled unlimited XRP minting.
Security & Exploits ·
XRP Ledger's developers disclosed a critical vulnerability in the network's payment engine that could have allowed an attacker to generate counterfeit XRP beyond the ledger's total supply. A researcher reported the flaw through the bug bounty program in September, and the maintainers patched and released the fix on September 25 in version 3.4.1, with over 80% of trusted validators running the patched software that same day.
The vulnerability was an integer overflow that lay dormant since 2015, when the current payment engine was first written. The bug could be triggered by a single transaction consuming hundreds of specially constructed offers from the order book. When the accumulated debt surpassed the system's maximum storable value, it wrapped around to a negligible sum, causing the buyer to pay nearly nothing while sellers received full payment—the gap constituting newly created XRP. The ledger's built-in safety mechanism meant to prevent XRP creation relied on identical arithmetic and thus failed to detect the overflow.
The patch bypassed the ledger's standard amendment process, marking the first time a transaction-processing change shipped without the usual two-week validator voting window since the amendment system's introduction over a decade ago. The team cited severity and the need to avoid leaving the vulnerability exploitable while the open-source code was reviewed. No evidence exists that the bug was ever exploited.