Executive Summary

CVE-2025-69893 is a side-channel vulnerability in the BIP-39 mnemonic processing implementation on certain Trezor hardware wallets (Trezor One, Trezor T, and Trezor Safe running specific firmware versions). The vulnerability arises because the mnemonic processing function does not execute in constant time, allowing attackers with physical access during the device's initial setup or when unlocked to collect side-channel traces.

Using profiling-based Deep Learning Side-Channel Analysis (DL-SCA), an attacker can analyze these traces to recover the mnemonic recovery seed (the backup phrase), which can then be used to steal the assets stored on the device.

The issue was fixed by modifying the vulnerable function to use a constant-time linear search instead of a binary search and by storing a binary copy of the recovery seed directly, thus mitigating timing side-channel leakage.

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Impact Analysis

If an attacker gains physical access to your Trezor hardware wallet while it is unlocked or during the initial setup phase, they can exploit this vulnerability to extract your BIP-39 mnemonic recovery seed through side-channel analysis.

With the recovered mnemonic code, the attacker can gain full control over your cryptocurrency assets by restoring your wallet elsewhere and transferring your funds.

This compromises the secrecy of your backup seed, violating the security model of Trezor devices which are designed to display the backup seed only once and keep it secret.

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Detection Guidance

This vulnerability is a side-channel attack affecting the BIP-39 mnemonic processing on Trezor hardware wallets and requires physical access to the device in an unlocked state. Detection involves verifying the firmware version of the Trezor device to see if it falls within the vulnerable range (Trezor One v1.13.0 to v1.14.0, Trezor T v1.13.0 to v1.14.0, and Trezor Safe v1.13.0 to v1.14.0).

Since this is a hardware and firmware vulnerability related to timing side-channel leakage, it cannot be detected via network commands or typical system scans.

To check the firmware version on your Trezor device, you can use the official Trezor Suite software or the device interface itself. There are no specific network or system commands to detect this vulnerability.

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Mitigation Strategies

The immediate mitigation step is to update the firmware of your Trezor hardware wallet to a version that includes the patch for this vulnerability.

• Ensure your device firmware is updated beyond versions v1.14.0 where the fix was applied.
• Avoid leaving your Trezor device physically accessible and unlocked to untrusted parties.
• Consider using devices or firmware configurations that do not use BIP-39 backups or use bitcoin-only firmware or SLIP-39 backups, which are not affected.

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Compliance Impact

The vulnerability allows an attacker with physical access to extract the BIP-39 mnemonic recovery seed from Trezor hardware wallets through side-channel analysis, compromising the secrecy of the backup seed.

This breach of backup secrecy could lead to unauthorized access to sensitive cryptographic assets, which may impact compliance with data protection standards and regulations such as GDPR and HIPAA that require safeguarding sensitive information against unauthorized disclosure.

However, the vulnerability requires physical access and an unlocked device, and the issue has been patched to mitigate the risk.

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