Mozilla has introduced Web Serial support to its Firefox Nightly browser, allowing users to communicate directly with hardware via serial ports. The update, found in version 151.0a1, marks the end of a thirteen-year wait for the API's implementation in the browser.
According to theregister.com, the Web Serial API enables the browser to interact with devices such as 3D printers, microcontrollers like Arduino and ESP32, and smart home dashboards like ESPHome. The feature also supports devices capable of emulating serial ports over USB or Bluetooth.
While Google Chrome has supported Web Serial since 2021, Mozilla previously resisted the technology due to security risks. The outlet reported that the browser's developers long viewed the interface as a potential vulnerability.
A shift in security stance
Six years ago, Mozilla engineers argued against the API's safety. "We don't believe that user consent is adequate protection for anything that provides this level of capability," wrote Martin Thomson, a distinguished engineer at Mozilla, in a 2020 GitHub discussion.
Thomson noted that serial access represents a "relic from an age where a physical connection conferred a great deal of trust." He warned that many devices offer administrative control to anything connecting via this interface without authentication, often granting privileges that exceed those of a root user.
Mozilla's position began to soften two years later. Firefox CTO Bobby Holley indicated that the company was open to shipping WebSerial using an add-on-gaining mechanism similar to WebMIDI, provided the consent prompts were easy for users to understand.
Despite this change, Mozilla still opposes WebUSB and WebHID due to similar security and privacy concerns. The company's shift appears driven by the need to remain competitive in an ecosystem where Chromium-based browsers like Edge, Opera, and Vivaldi already offer the feature.
Apple's WebKit team continues to oppose Web Serial, WebUSB, and WebHID, citing risks related to fingerprinting and security. However, as Mozilla explores deeper AI integration within Firefox, the utility of hardware interaction may outweigh these long-standing privacy objections.
