CVE-2025-15645: Ledger Nano X, Flex, Stax MCU Firmware Update Denial of Service

Severity: medium (CVSS 4.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-19 · updated 2026-07-24
Weakness: CWE-1284

Description

Ledger Nano X, Flex, and Stax devices contain a denial of service vulnerability in the MCU firmware update process due to missing validation of the reset_handler parameter during firmware flashing. An attacker can provide a crafted reset_handler address pointing to invalid memory or attacker-controlled code to cause the device to enter an unrecoverable fault state during boot, resulting in permanent loss of operability.

Affected products

Ledger Flex: before 1.2.2 — fixed in 1.2.2
Ledger Nano X: before 2.4.2 — fixed in 2.4.2
Ledger Stax: before 1.6.2 — fixed in 1.6.2

How to fix

Upgrade to a fixed version: Ledger Flex 1.2.2; Ledger Nano X 2.4.2; Ledger Stax 1.6.2. Check the vendor advisory for mitigations.

References

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