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1. A rival developer flags default signature reporting in Ledger's toolkit
Kaloyan Kosev, a developer at wallet maker Ambire, said on November 10 that the software kit wallet apps use to communicate with Ledger hardware sends details of every signature to Ledger servers by default. Ledger Donjon, the company's security research team, replied that the lookups are part of how Ledger Clear Signing works, run in wallet software rather than device firmware, and are not retained.
The exchange has turned into a public debate over privacy defaults in self-custody tools. Kosev's core argument is not that Ledger devices themselves are secretly transmitting data, but that the developer toolkit sitting between a wallet app and the hardware is configured to report signing activity unless the wallet developer actively turns that behavior off. In his view, privacy should be the starting point, with any data sharing left to users who explicitly choose it.
Ledger's position is that the network calls serve a security function. Without them, the company says, its devices could not show readable descriptions of many complex transactions, which would push users back toward approving actions they cannot properly inspect.
Hardware wallets such as Ledger's devices are built to keep private keys offline, signing transactions inside a dedicated chip so that the keys never touch an internet-connected computer. The device, however, still depends on companion software to build transactions, broadcast them and, increasingly, explain them to the user. That companion layer is where the current dispute is centered, and it is also where the trade-off between convenience and privacy is hardest to avoid.
2. What Kosev says the software sends
In his post on X, Kosev said each signature triggers a request to a Ledger server. The information in that request, he said, includes the blockchain network involved, the destination address, the device model and firmware version, the versions of the software apps in use, and whether the user approved the transaction blind.
Blind signing refers to approving a transaction that the hardware wallet cannot display in human-readable form. Instead of seeing a clear description, such as the token, amount and recipient, the user sees a raw hash or an opaque string of data. Security researchers have long treated blind signing as risky because it leaves users unable to verify what they are authorizing, a weakness that scammers can exploit by disguising malicious approvals as routine ones.
Kosev said the reporting has been switched on by default since version 1.16 of a Ledger software package called context-module. He argued that a wallet toolkit handling such sensitive information should keep it local unless a user decides otherwise.
The combination of fields Kosev listed is what makes the issue sensitive. A destination address paired with device and app details could, in principle, help link on-chain activity to a particular user's setup. Even if the data is not stored, privacy advocates generally prefer that such information never leave the user's environment in the first place.
3. The code was public before the post
Kosev's post did not reveal hidden code. The behavior he described is visible in Ledger's own public records. The changelog for the context-module package lists a "blind signing reporter" introduced in version 1.16.0. A later release, version 2.1.0, pointed that reporter at a production endpoint, blind-signing.api.ledger.com.
On October 8, a Ledger engineer merged a code change titled "Turn multichain sign reporter on." That change posts signing events for transactions on Ethereum and Solana, extending the reporting beyond a single network.
Because the code was published openly, any wallet developer reviewing Ledger's toolkit updates could have spotted the change. The episode illustrates a familiar pattern in open-source software: functionality can be fully public for weeks or months before it attracts wider attention, often once someone frames it in terms users care about.
4. Ambire changed its own setup weeks earlier
Ambire was aware of the reporting well before Kosev's public post. On September 24, he opened a pull request in Ambire's code that keeps the reports turned off unless a user chooses to enable them. Ambire merged that change on September 30.
Kosev said none of the affected Ledger toolkit releases ever made it into Ambire's live application. In other words, Ambire users connecting Ledger devices were not exposed to the default reporting through Ambire's production app.
That timeline shapes how the dispute should be read. Kosev raised the issue publicly after his own team had already addressed it for its users, framing the post as a broader argument about how the toolkit should behave for every wallet that depends on it, rather than as a report of an active leak in Ambire's product.
5. What is Ledger Clear Signing?
Ledger Clear Signing is the company's feature for showing transaction details on the hardware device in plain, readable terms instead of raw data, so users can confirm what they are approving. It is designed as the counterpart to blind signing.
To translate complex smart contract interactions into readable descriptions, Clear Signing relies on descriptor files written to ERC-7730, an Ethereum standard for describing how contract calls should be presented to users. These files map technical function calls and parameters to labels a person can understand.
Ledger Donjon said in its reply on X that those descriptor files are too large to keep on the device itself. As a result, the default context module queries Ledger's servers during the signing process to retrieve the right description. To find a match, the module must send enough information about the transaction for the server to identify which descriptor applies.
Donjon said Ledger does not keep the data it receives through these lookups. The team also noted that wallet developers are not locked into Ledger's default approach and can substitute their own module, for example one that sources descriptors differently or performs the lookups through their own infrastructure.
6. Does Ledger firmware phone home?
No. According to both Ledger and an independent security researcher, the reporting code lives in the software development kit used by wallet apps, not in the firmware running on Ledger hardware.
Some early reactions had placed the code in the wrong layer. Lefteris Karapetsas asked on X whether devices running the latest Ledger firmware were contacting Ledger and handing the company a record of every signature. The question reflected a common concern among hardware wallet users, many of whom choose such devices specifically to keep their keys and activity isolated from internet-connected systems.
Ledger Donjon and Yu Xian of blockchain security firm SlowMist, who posts under the name Cos, both clarified that the behavior sits in the SDK. That distinction matters. Firmware controls the device itself and the protection of private keys, while the SDK is code that wallet developers bundle into their own desktop, mobile or browser applications. Whether the reporting runs at all therefore depends on which wallet app a user connects to and how that app's developers have configured Ledger's toolkit.
7. The real argument is about defaults
Stripped of the initial confusion, the disagreement comes down to a question of defaults. Ledger says the lookups are necessary for Clear Signing to work out of the box and that the data is not stored. Kosev says that, whatever the purpose, a toolkit used across many wallets should not send signature details to a central server unless a user opts in.
Default settings carry outsized weight in software. Many developers integrate libraries as shipped, without reviewing every configuration option, so whatever behavior a toolkit enables by default tends to become the behavior most end users experience. That is why privacy advocates focus so heavily on whether data sharing is opt-in or opt-out, rather than simply whether it can be disabled.
The tension is not unique to Ledger. Any feature that improves what users see on a small hardware screen by fetching information from elsewhere creates a choice about where that information comes from and who learns about the request. A server-side lookup is simple and keeps descriptions up to date, but it means some transaction details leave the user's machine. Keeping everything local protects privacy but requires a different way of distributing and updating the descriptor files, which Ledger says are too large to store on the device.
For wallet developers, the practical takeaway is that the behavior can be controlled. Ambire's change shows that the reporting can be kept off unless a user enables it, and Ledger has said developers can replace its context module entirely. For users, the exposure depends on the software wallet they pair with their device rather than on the hardware itself.
8. Ledger under scrutiny after a separate reseller attack
The debate comes at a sensitive time for the company. About a month earlier, Ledger devices sold through a reseller in Southeast Asia were drained in a separate attack, an incident unrelated to the signature reporting but one that had already put the security of Ledger's supply chain and user experience under a spotlight.
Hardware wallet makers sell trust as much as technology, and episodes like these tend to draw intense scrutiny from a user base that is highly attentive to privacy and security. How Ledger and wallet developers settle the question of default reporting in its toolkit is likely to be watched closely by both groups, particularly as Clear Signing becomes a more central part of how users approve transactions across Ethereum and Solana.
For now, the immediate decision rests with individual wallet teams. Each one integrating Ledger's toolkit can review the context module's configuration, decide whether to keep the default reporting, turn it off as Ambire did, or replace the module with its own approach, and explain that choice to the people who rely on its app to sign transactions.