CVE-2025-69893 Overview
A side-channel vulnerability exists in the implementation of BIP-39 mnemonic processing in Trezor hardware wallets. This vulnerability affects 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. The flaw originates from the BIP-39 standard guidelines, which induce non-constant time execution and specific branch patterns during word searching operations. An attacker with physical access to a device during the initial setup phase can collect a single side-channel trace and, by utilizing profiling-based Deep Learning Side-Channel Analysis (DL-SCA), recover the mnemonic code and subsequently steal cryptocurrency assets.
Critical Impact
Physical attackers can recover mnemonic seed phrases through side-channel analysis during device setup, potentially leading to complete theft of cryptocurrency assets stored in affected hardware wallets.
Affected Products
- Trezor One v1.13.0 to v1.14.0
- Trezor T v1.13.0 to v1.14.0
- Trezor Safe v1.13.0 to v1.14.0
Discovery Timeline
- 2026-04-14 - CVE-2025-69893 published to NVD
- 2026-04-16 - Last updated in NVD database
Technical Details for CVE-2025-69893
Vulnerability Analysis
This vulnerability is classified as a side-channel attack (CWE-385: Covert Timing Channel), exploiting timing variations in the BIP-39 mnemonic word search implementation. The BIP-39 standard defines a wordlist of 2048 words used to generate mnemonic seed phrases for cryptocurrency wallets. When a user enters or generates their mnemonic phrase during wallet setup, the firmware performs word validation operations that exhibit non-constant time behavior.
The vulnerability is exploitable only with physical access to the device, limiting the attack surface to scenarios such as supply chain compromise, temporary device access, or malicious retail environments. However, the confidentiality impact is high because successful exploitation allows complete recovery of the seed phrase, granting the attacker full control over all associated cryptocurrency addresses and funds.
Root Cause
The root cause lies in the BIP-39 standard implementation guidelines that inherently create timing variations during word lookup operations. When the firmware searches for mnemonic words in the wordlist, it employs algorithms that do not execute in constant time. This creates observable timing differences and branch patterns that can be measured through electromagnetic emanations or power analysis. The non-constant time execution leaks information about which words are being processed, enabling statistical analysis to recover the complete mnemonic phrase.
Attack Vector
The attack requires physical access to the target Trezor device during the initial setup phase when the mnemonic seed is being generated or entered. The attacker positions measurement equipment (such as an electromagnetic probe or power analysis setup) near the device to capture side-channel traces. A single trace capture during the mnemonic processing operation is sufficient for exploitation.
Using Deep Learning Side-Channel Analysis (DL-SCA) techniques, the attacker processes the captured trace data through trained neural network models that have been profiled against similar devices. These models can identify patterns corresponding to specific BIP-39 words, ultimately reconstructing the complete mnemonic phrase. Once recovered, the attacker can derive all private keys and transfer cryptocurrency assets to their own wallets.
Detection Methods for CVE-2025-69893
Indicators of Compromise
- Evidence of physical tampering or unauthorized access to hardware wallet devices
- Unexpected electromagnetic measurement equipment detected near wallet setup environments
- Unauthorized fund transfers from wallets initialized on potentially compromised devices
- Signs of extended device handling by third parties during purchase or setup
Detection Strategies
- Implement physical security monitoring in environments where hardware wallets are initialized
- Use tamper-evident seals on hardware wallet packaging to detect supply chain compromise
- Monitor blockchain transactions for unexpected outflows from addresses associated with potentially affected devices
- Conduct periodic security audits of hardware wallet initialization procedures
Monitoring Recommendations
- Maintain chain-of-custody documentation for hardware wallets from purchase through initialization
- Monitor cryptocurrency addresses for any unauthorized transaction activity
- Review vendor security advisories regularly for firmware updates addressing side-channel vulnerabilities
- Consider hardware wallet attestation mechanisms to verify device integrity
How to Mitigate CVE-2025-69893
Immediate Actions Required
- Update all affected Trezor devices to the latest firmware version that includes the security patch
- Initialize or re-initialize hardware wallets only in physically secure, private environments
- Transfer assets from wallets that may have been set up on compromised devices to new wallets with freshly generated seed phrases
- Verify firmware integrity before use by checking cryptographic signatures
Patch Information
Trezor has released a security patch addressing this vulnerability. Users should update their devices to the latest available firmware version. The Trezor Vulnerability Fix Advisory provides detailed information about the patch and update instructions.
Workarounds
- Ensure wallet initialization occurs in a physically isolated environment free from potential eavesdropping equipment
- Use a Faraday cage or shielded room during mnemonic generation if high-security is required
- Never initialize hardware wallets in public spaces, retail stores, or untrusted environments
- Consider using additional passphrase protection (BIP-39 passphrase) as an extra layer of security that would not be captured by this side-channel attack
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
