- A decade-old integer overflow in the XRP Ledger payment engine could have allowed an attacker to mint spendable XRP far beyond the 100 billion supply cap.
- The bug was reported on Sept. 22 by Veria Labs’ AI agent and fixed three days later in an emergency xrpld 3.4.1 release that bypassed the usual amendment vote.
- Developers found no evidence of exploitation on any public network; Veria received the maximum $250,000 bounty.
XRP Ledger developers disclosed on Oct. 9 that an integer overflow in the network’s payment engine, present since the code was written in 2015, could have let an attacker create and spend new XRP in violation of the ledger’s fixed supply rules, according to the official vulnerability disclosure report.
The flaw affected how the engine summed XRP amounts when a single payment consumed many order-book offers. Balances are stored as 64-bit integers with a fixed maximum; when the total exceeded that limit it wrapped around to a small number instead of erroring. The engine then paid each offer owner in full while charging the buyer only the wrapped total, minting the difference as new, spendable XRP, the report states.
The attack “could not be triggered by accident,” requiring “hundreds of offers priced in a way no real trader would use, followed by a payment built specifically to consume them all at once,” per the disclosure. RippleX engineers reproduced the exploit on a standalone server the same day it was reported, confirmed the minted XRP could be spent in a follow-up payment, and raised the severity from major to critical.
Security firm Veria Labs said its AI agent discovered the chained vulnerabilities and built a working proof-of-concept. Co-founder Cayden Liao wrote on X that one exploit transaction could have created about 18 trillion XRP, or 184 times the 100 billion token launch supply. Veria was awarded the program’s maximum $250,000 bounty, which Liao described as the largest known payout for a vulnerability found entirely by an AI agent, according to the firm’s blog post.
The fix shipped in xrpld version 3.4.1 on Sept. 25, three days after the Sept. 22 report. More than 80% of default Unique Node List validators were running the patched software that day. For the first time in more than a decade, developers skipped the normal two-week amendment vote that requires more than 80% support, because publishing the source before activation would have left the flaw public and exploitable for weeks, the XRP Ledger Foundation explained.
The foundation stressed that no new XRP was created. “XRP’s supply was fixed at 100 billion when the XRP Ledger launched, and no transaction is allowed to create more. This bug was a way around that rule, and 3.4.1 fixed it,” @XRPLF posted. About 99.986 billion XRP remain in circulation as fees are burned. The same release also addressed a separate Batch transaction wrapper validation issue that activated via normal amendment on Oct. 9.
The episode underscores both the growing role of AI in vulnerability discovery and the operational challenges of patching live decentralized networks without creating new attack windows. Developers said they are increasing formal verification, AI adversarial testing, and bounty incentives in response.
