Ledger OLED screen power side channel could partially reveal PIN or recovery phrase

August 7, 2019LedgerLow

Who is affected

An attacker able to measure power on the USB line during setup or PIN entry could partially infer the displayed PIN or recovery words on a Ledger Nano S or Nano X. Ledger describes the attack as theoretical and non-critical.

What happened

Security researcher Christian Reitter reported to Ledger, through its bug bounty programme on 7 May 2019, that the OLED displays of the Ledger Nano S and Nano X leak information through power consumption. The CVE record (CVE-2019-14354) states that the power drawn in each row-based display cycle depends on how many pixels are lit, which can partially reveal what is on screen, such as the PIN or the BIP39 recovery phrase while they are displayed.

According to Ledger, an attacker would need to measure the device’s power draw through the USB connection, for example with a hardware implant in the USB cable, while secrets are on screen. Ledger says it reproduced the setup with a modified cable and an oscilloscope and was able to distinguish words of a recovery phrase. The CVE record notes the side channel is not relevant to a stolen device that is not displaying secret data; NVD scores it 2.4 (low).

Ledger rated the issue non-critical, describing it as theoretically possible but not demonstrated in practice and less practical than a hidden camera. Ledger states the Ledger Blue, with an LCD screen, is not affected. It announced countermeasures, including randomly varying screen parameters and showing sensitive data in inverted-pixel boxes, for Nano S and Nano X firmware updates scheduled for Q4 2019, and says such vulnerabilities can never be fully solved. Reitter coordinated disclosure with other affected vendors. Ledger published its bulletin on 7 August 2019.

What Ledger advises:

Update the Nano S and Nano X when the firmware with countermeasures is released.
Set up the device yourself in a safe place and store the recovery phrase securely.

Sources

Independent reporting and research this entry was checked against.

Learn more

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Fault Injection

Fault injection disturbs a chip's voltage, clock or electromagnetic environment so that it skips a security check or leaks data.

Side-Channel Attack

A side-channel attack in cryptocurrency and blockchain targets indirect information, like power usage or timing, to extract sensitive data from a system or device.

Secure Element

A secure element is a tamper-resistant chip built to store secrets and resist physical attacks such as side-channel analysis and fault injection.

Evil Maid Attack

An evil maid attack is a physical security threat where an attacker gains temporary unsupervised access to a hardware wallet to tamper with it, install malicious firmware, or extract private keys.

Cite this entry

WalletInsights. “Ledger OLED screen power side channel could partially reveal PIN or recovery phrase”. Hardware wallet security incident tracker. Last verified November 4, 2026. https://walletinsights.io/en/security-incidents/ledger-oled-screen-power-side-channel-2019/

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