Dell Inspiron 15 3520 and Vostro 3420/3520 System BIOS

Restart required

Do not turn off your computer or disconnect from the power source while updating the BIOS as this could harm your computer. During the update, your computer will restart and you may briefly see a black screen.

Before updating, please read the installation instructions and important information noted below.

Driver Id : 86P3H

Importance : Critical

Version : 1.42.0, 1.42.0 Latest version Recommended version Latest and Recommended version

Release Date : 20 Jul 2026

Download Type : System BIOS

Category : BIOS

This package contains the Dell system BIOS update. BIOS is a firmware package that is embedded on a small memory chip on the system board. It controls the keyboard, monitor, disk drives, and other devices. This update addresses the Dell Security Advisory (DSA). A security advisory is a statement when a security vulnerability impacts a product, and a remedy is available for the vulnerability.

Download Files

File Format: This file format consists of a BIOS executable file. The Universal (Windows/MS DOS) format can be used to install from any Windows or MS DOS environment.

File Name: Inspiron_Vostro_3420_3520_1.42.0.exe

File size: 117.31 MB

To ensure the integrity of your download, please verify the checksum value.

MD5: b050578f2e6adda028f10fe467ed0e38

SHA1: f3dd7df051168327259d7d5db3b70846a2d128a5

SHA-256: dc106f9ba57f50040f0f0c836f675a9fbc7357010462fcc1859159bf7c8431d6

Download .EXE

File Format: This file format consists of a BIOS Recovery image file. This file is used for the System BIOS Recovery process to recover a system from a corrupted BIOS.

File Name: BIOS_IMG.rcv

File size: 117.3 MB

To ensure the integrity of your download, please verify the checksum value.

MD5: 107a7f31a3c21d99d78c74ed67465bc8

SHA1: f0e5996696d9a34d47d6d36de31574001cec84c0

SHA-256: d0e51ecc98153a7197a35fc6b58f5b7a67f30d19427e3827c20f64a00d98c6bf

Download .RCV

Fixes & Enhancements

- This release contains security updates as disclosed in the Dell Security Advisory DSA-2026-212. The DSA details are published on the Security Advisories, Notices, and Resources page, once they are publicly available. For more information about the release schedule, see Dell Client Drivers and Downloads Update Release Schedule.
- Fixed the issue where the Help screen in the Dell Firmware Update Utility is not fully displayed.
- Fixed the issue where an unsupported NoReboot option is incorrectly displayed in the Dell Firmware Update Utility Help screen.

Important Information

- This BIOS contains the new 2023 Secure Boot Certificates.
- Once the BIOS is upgraded, you cannot downgrade the BIOS to versions earlier than 1.38.0. BIOS downgrades are restricted when there are security updates and important fixes with earlier versions that impact the functionality of the system.
- BIOS updates take no more than 5 minutes to be installed on your system. You can install the updates in the background while using the system.

Compatible Systems

Inspiron 15 3520

Vostro 3420

Vostro 3520

Installation instructions

Updating the BIOS from Windows

Note 1: Before updating the BIOS, ensure that you suspend BitLocker encryption on a BitLocker-enabled system. If BitLocker is not enabled on your system, you can ignore this step. For information about how to disable BitLocker, see How to Enable or Disable BitLocker with TPM in Windows at support.dell.com.
Note 2: Do not turn off the power or interrupt the BIOS update process during the update.
Note 3: Your system requires a restart after installing the BIOS. The restart can be deferred but must be completed to ensure that the update is installed.

Download and Installation
1. Click Download File.
2. Click Save to save the file to your hard drive.
3. Browse to the location where you downloaded the file.
4. Double-click the new file.
The system restarts automatically and updates the BIOS at the system startup screen. After the BIOS update is complete, system restarts again.

Updating the BIOS from BIOS Boot Menu (independent of operating system)

Note 1: Before updating the BIOS, ensure that you suspend BitLocker encryption on a BitLocker-enabled system. If BitLocker is not enabled on your system, you can ignore this step. For information about how to disable BitLocker, see How to Enable or Disable BitLocker with TPM in Windows at support.dell.com.
Note 2: Do not turn off the power or interrupt the BIOS update process during the update.
Note 3: Your system requires a restart after installing the BIOS. The restart can be deferred but must be completed to ensure that the update is installed.

Installation
1. Copy the downloaded file to a USB drive. You do not need a bootable USB drive.
2. Insert the USB drive into any USB port.
3. Power on the system.
4. At the DELL logo screen, press F12 to access the one-time boot menu.
5. Select BIOS Flash Update in the Other Options section.
6. Click the ... button to browse the USB drive to locate the downloaded file.
7. Select the file and click OK.
8. Verify the existing system BIOS information and the BIOS update information.
9. Click Begin Flash Update.
10. Review the Warning message and click Yes to proceed with the update.
The system restarts and displays a Flash Progress bar at the Dell logo screen. The system restarts again when the Flash update is complete.