CVE-2025-15645

Ledger Nano X, Flex, Stax MCU Firmware Update Denial of Service

MEDIUM

4.6

CVSS Score

Published: May 19, 2026 at 09:41 PM UTC

Updated: July 24, 2026 at 09:23 AM UTC

4 products affected across 2 vendorsLedgerNano XFlex

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Severity

MEDIUM4.6

Exploit prediction

EPSS 0.2%

SSVC

No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Ledger · Ledger Cli

95%

v < 2.4.2

Affected range stops below 2.4.2, so it looks safe — our inference, not a vendor statement

Flex · Ledger

60%

v < 1.2.2

Affected range stops below 1.2.2, so it looks safe — our inference, not a vendor statement

Nano X · Ledger

60%

v < 2.4.2

Affected range stops below 2.4.2, so it looks safe — our inference, not a vendor statement

Stax · Ledger

60%

v < 1.6.2

Affected range stops below 1.6.2, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://donjon.ledger.com/lsb/021/

References (3)

Source: cverecord

https://www.ledger.com/security-bulletin

Third Party Advisory

Source: cverecord

https://www.vulncheck.com/advisories/ledger-nano-x-flex-stax-mcu-firmware-update-denial-of-service

Vendor Advisory

Source: cverecord

https://donjon.ledger.com/lsb/021/

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.6MEDIUMVulnCheck

Attack Vector: PHYSICAL
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: NONE
Integrity: NONE
Availability: HIGH

Vector?

Quick Info

StatusDEFERRED

CWE

CWE-1284

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