In the wake of the attack on Binance’s hot-wallet infrastructure last week, a wave of major crypto exchanges has moved quickly to reassure customers by publishing how much of their holdings sit offline in cold storage versus online in hot wallets.
The disclosures matter because they directly affect how quickly an attacker could access user funds if hot wallets are compromised—though cold-storage ratios are only one part of exchange security.
Key takeaways
- Gate introduced a “Proof of Security” framework, reporting 88.26% of assets in cold storage and 11.74% in hot wallets, with cold storage claimed to cover 104.58% of customer assets under extreme scenarios.
- Coinbase said more than 99% of customer assets are held in offline cold storage, with excess assets continuously rebalanced to cold wallets.
- Upbit (Dunamu) disclosed it held 99.17% of assets in cold storage and 0.83% in hot wallets as of September 2026, positioning it above South Korea’s regulatory 80% minimum.
- Exchanges’ reported cold-wallet shares may not be directly comparable due to different asset bases and reporting periods.
- Regulators have warned that both hot and cold systems can be undermined through compromised signing setups, access control failures, or fraudulent internal approvals.
Gate’s “Proof of Security” disclosure
Gate said that last week’s incident involving Binance prompted broader customer questions about how exchanges safeguard assets when hot infrastructure is attacked. In response, Gate launched its “Proof of Security” (PoSEC) framework on Thursday.
According to Gate, 88.26% of its total assets are held in cold storage and 11.74% in hot wallets. Gate further claims that its cold storage can cover 104.58% of customer assets even in a worst-case scenario where hot wallets are completely drained. The exchange added that the figures are still undergoing review by an independent third-party audit firm.
By choosing to publish a ratio-based coverage claim tied to an extreme scenario, Gate is effectively going beyond a simple “how much is cold” statement—at least in terms of what it is trying to measure for customers: not just storage location, but whether offline holdings can absorb a complete hot-wallet loss.
Binance incident prompts wider transparency
The disclosures come after threat actors attacked Binance’s hot-wallet infrastructure last week, stealing approximately $6.36 billion, with most of the theft occurring in about 20 minutes, according to TRM Labs. Binance CEO Richard Teng said the “vast majority” of user assets are held in cold wallets, but Binance has not provided a precise cold-vs-hot split in the wake of the incident.
That gap—customers knowing that “most” assets are offline, but lacking exact ratios—appears to be driving the new round of exchange transparency. Several firms have now published concrete cold-wallet percentages rather than broad assurances.
Coinbase, Upbit and South Korea’s regulatory pressure
Coinbase addressed the question directly in a blog post published Wednesday. The company said it holds more than 99% of customer assets in offline cold storage and that it continuously rebalances excess assets to cold storage.
Coinbase’s post framed its disclosures as a response to customer concerns about how its own controls would prevent a comparable outcome to the Binance hack.
Meanwhile, Upbit—described as the largest cryptocurrency exchange in South Korea—confirmed in a disclosure that it held 99.17% of assets in cold wallets and 0.83% in hot wallets as of September 2026. Upbit’s data was already provided to South Korea’s Financial Supervisory Service, and the company emphasized that its cold storage share is the highest among the country’s five major KRW-based exchanges reported in the regulatory context.
In an explanation provided to Cointelegraph, a spokesperson for Upbit’s parent company Dunamu said the 99.17% figure is “substantially above the regulatory minimum of 80%” and that the exchange’s goal is to keep hot wallet holdings at an absolute minimum, targeting below 1% of customer digital assets.
Earlier reporting cited Financial Supervisory Service figures showing that other South Korean exchanges reported lower cold-wallet shares at the end of September: Bithumb at 94.76%, Coinone at 85%, Digital X (formerly Korbit) at 82.79%, and GOPAX at 80.54%.
OKX, for its part, pointed to an existing security overview updated on Sept. 18, 2026, stating it holds more than 95% of client crypto assets in cold wallets and less than 5% in hot wallets.
Why cold-storage ratios aren’t the whole security story
While cold-storage percentages are an important signal, the reports also highlight a complication: the ratios are not necessarily directly comparable across exchanges. Different reporting periods and different calculation methods—such as what asset base is used for the numerator and denominator—can make two “cold storage” percentages reflect different things.
More importantly, offline storage does not eliminate risk by itself. Even with a large share of assets kept offline, exchanges can still face attacks that compromise transaction authorization systems, weaken access controls, or allow internal approval processes to be abused. In other words, attackers may not need to drain hot wallets to cause operational damage or enable fraudulent transfers.
Hong Kong’s Securities and Futures Commission previously warned, in an August 2025 circular, that weaknesses affecting signing processes and access controls could compromise both hot- and cold-wallet infrastructure.
That regulatory perspective helps explain why the new disclosures—though likely reassuring to many customers—should be interpreted as part of a broader assessment of exchange security practices rather than the final proof that funds are safe.
As more exchanges publish custody breakdowns in the wake of the Binance incident, the next point to watch is whether this transparency expands beyond “cold vs hot” percentages into clearer disclosures about controls around signing systems, access management, and recovery processes. Customers may also want to pay attention to how consistently exchanges define and calculate their storage ratios, so comparisons remain meaningful.
