Mt. Gox Extends Repayment Deadline To October 2026

The now-defunct crypto exchange Mt. Gox has pushed back the deadline for its creditor repayments by a year just four days before its deadline at the end of the month.

“As it is desirable to make the Repayments to such rehabilitation creditors to the extent reasonably practicable, the Rehabilitation Trustee, with the permission of the court, has changed the deadline for the Repayments from October 31, 2025 (Japan Standard Time) to October 31, 2026 (Japan Standard Time).” the exchange’s rehabilitation trustee said. 

Many Creditors Have Still Not Received Their Repayments

The exchange’s rehabilitation trustee said that it has “largely completed” the base repayment, early lump-sum repayment, and intermediate repayment for creditors that were able to complete their eligibility procedures without any issues. 

There are, however, still many creditors that have not received their repayments either because they failed to complete the necessary procedures or due to issues that arose during the process.

Today’s announcement marks the third time the defunct exchange has pushed back the deadline. 

Creditors Have Waited Over A Decade For Repayments

Mt. Gox was a Tokyo-based exchange that was founded in 2010. It went on to become one of the top exchange platforms for trading Bitcoin at the time. However, a security breach in 2014 saw 850,000 BTC stolen from the platform. This forced the exchange to halt withdrawals and file for bankruptcy protection. 

In September 2023, the platform’s trustee announced that it aims to reimburse a portion of the original losses to creditors with recovered assets. These assets include 142,000 Bitcoin and 143,000 Bitcoin Cash, as well as fiat currency totaling 69 billion Japanese yen, which is around $510 million.

Since the middle of 2024, several creditors have said that they have received their payments through the crypto exchanges Kraken and Bitstamp. An announcement made by the rehabilitation trustee in March this year said that 19,500 creditors have been repaid. 

On-chain data from Arkham Intelligence shows that Mt. Gox still holds 34,689 BTC. With the crypto trading at $115,557 as of 4:21 a.m. EST, the defunct platform’s holdings are valued at more than $4 billion. 

Mt. Gox’s Bitcoin holdings (Source: Arkham Intelligence) 

Mt. Gox Codebase Deemed “Critically Insecure” By Claude AI

Mt. Gox’s CEO, Mark Karpelès, recently had the exchange’s 2011 codebase analyzed by Anthropic’s Claude AI model.

In the analysis, the CEO provided various other data along with the exchange’s codebase, including the git history, access logs, and dumps released. 

So I tried feeding MtGox’s 2011 codebase and various data (git history, access logs, dumps released by hacker, etc) to @AnthropicAI‘s Claude, and let it analyze its way through all the stuff.

The result:https://t.co/r8oxCUW3Qp

— Mark Karpelès (@MagicalTux) October 26, 2025

After analyzing the code, the AI model labelled the defunct exchange’s codebase as “feature-rich,” but said that it is also “critically insecure.” 

“The developer (Jed McCaleb) demonstrated strong software engineering capabilities in terms of architecture and feature implementation, creating a sophisticated trading platform in just 3 months,” the AI said in its analysis. 

“However, the codebase contained multiple critical security vulnerabilities that were targeted in the June 2011 hack. Security improvements made between ownership transfer and the attack partially mitigated the impact,” the AI added. 

The attacker managed to gain access to Mt. Gox’s database through an “undocumented WordPress SQL injection.” Thereafter, the database was dumped to reveal mixed password hashes, including the salted passwords belonging to active users and the MD5 protected passwords that belonged to inactive users. 

With the breach, the attacker was then able to fraudulently manipulate account balances via the admin interface. He then stole approximately 2,000 BTC through early withdrawals, before crashing the price from $17 to $0.01. Thereafter, the attacker attempted to exploit Mt. Gox’s $1,000 withdrawal limit to drain the exchange. 

While the attacker managed to steal 850,000 BTC from the exchange, the analysis showed that there were some mitigating factors. 

Claude AI said that security improvements, like the upgraded password hashing, SQL injection fix, proper withdrawal locking, transaction isolation, and the quick shutdown response, helped limit the damage. 

Karpelès said on X that he “didn’t get to look at the code before taking over,” adding that it was “dumped” on him “as soon as the contract was signed.” He then said that he has since learned that “due diligence goes a long way.” 

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