CVE-2021-43716: Epson EasyMP Auth Bypass Vulnerability

CVE-2021-43716 Overview

CVE-2021-43716 is a verification bypass vulnerability in EPSON EasyMP Network Updater version 1.20 (firmware identifier 150075647YWWV110). The vulnerability affects the firmware update mechanism for Epson projectors. An Epson projector can be updated by encrypted firmware delivered through USB, but the update routine fails to properly verify firmware authenticity. An attacker with physical or logical access to the update path can supply crafted firmware to alter device behavior. Details of the issue are published in the GitHub advisory for CVE-2021-43716.

Critical Impact
An attacker with USB access can load unverified firmware onto affected Epson projectors, undermining device integrity and enabling persistent implants.

Affected Products

EPSON EasyMP Network Updater Ver.1.20
EPSON projector firmware identifier 150075647YWWV110
EPSON EH-TW5350 projector (referenced in the advisory repository)

Discovery Timeline

2026-08-18 - CVE-2021-43716 published to NVD
2026-08-18 - Last updated in NVD database

Technical Details for CVE-2021-43716

Vulnerability Analysis

The vulnerability resides in the firmware update workflow used by EPSON EasyMP Network Updater Ver.1.20. The updater accepts encrypted firmware images delivered through USB and applies them to the projector. The verification logic does not adequately validate the authenticity or integrity of the supplied image before flashing.

An attacker who can present a crafted firmware payload through the USB update channel can bypass the intended verification step. This allows unauthorized firmware to be accepted as legitimate. Because projector firmware controls boot, network, and I/O behavior, the compromise can persist across reboots and evade software-layer defenses.

The advisory categorizes this as a firmware-level authentication and integrity failure. It aligns with common firmware verification weaknesses where cryptographic checks are either missing, incorrectly implemented, or applied to the wrong data segments. See the GitHub advisory for details.

Root Cause

The root cause is insufficient verification of firmware authenticity in the EasyMP Network Updater. The encrypted firmware format does not enforce a signature or integrity check that binds the payload to a trusted vendor key. Encryption alone does not establish authenticity, so a modified or attacker-supplied image can be accepted by the updater.

Attack Vector

Exploitation requires the ability to deliver firmware to the projector through USB. An attacker with brief physical access, or control over a workstation used to run the EasyMP Network Updater, can trigger the flawed update path. The attack does not require network reachability to the projector itself. The EPSS score is 0.203% (percentile 10.549), reflecting low observed exploitation activity.

No verified exploit code is publicly available. The vulnerability mechanism is described in prose in the referenced GitHub advisory and does not require synthetic code to characterize.

Detection Methods for CVE-2021-43716

Indicators of Compromise

Unexpected firmware version strings on Epson projectors that do not match vendor-published releases for 150075647YWWV110.
USB update activity on workstations running EasyMP Network Updater outside of scheduled maintenance windows.
Presence of the EasyMP Network Updater Ver.1.20 binary on endpoints not designated for projector administration.

Detection Strategies

Inventory devices running EasyMP Network Updater and correlate execution events with firmware update tickets.
Monitor USB mass storage insertion events on hosts that manage projectors and flag firmware image files transferred to those hosts.
Periodically capture and hash projector firmware version banners exposed over the management interface to detect drift.

Monitoring Recommendations

Log EasyMP Network Updater process launches and command-line arguments through endpoint telemetry.
Alert on USB device connections to projector-adjacent workstations outside change windows.
Track network traffic to and from Epson projectors for anomalous outbound connections that could indicate a compromised firmware payload.

How to Mitigate CVE-2021-43716

Immediate Actions Required

Restrict physical access to affected Epson projectors and to any USB ports used for firmware updates.
Limit installation of EasyMP Network Updater Ver.1.20 to authorized administrator workstations.
Require change-controlled procedures for any projector firmware update and verify firmware images against vendor-published hashes when available.

Patch Information

No vendor patch is referenced in the available advisory data. Consult Epson support channels and the GitHub advisory for CVE-2021-43716 for the latest remediation guidance and any updated firmware releases from the vendor.

Workarounds

Physically secure projector USB ports using port blockers or tamper-evident seals in shared or public spaces.
Segment projectors onto isolated VLANs with no route to sensitive assets to contain post-compromise impact.
Disable or uninstall EasyMP Network Updater on endpoints that do not require projector firmware management.

bash

# Example: block USB mass storage on Windows administrator workstations
# Set the Start value to 4 to disable the USBSTOR driver
reg add "HKLM\SYSTEM\CurrentControlSet\Services\USBSTOR" /v Start /t REG_DWORD /d 4 /f