CVE-2026-54257: Electron: Buffer performs incorrect byte length calculations resulting in heap buffer under/overflow

Synopsis

A heap buffer under/overflow vulnerability affects the Electron framework, specifically versions 42.3.1 through 42.3.3, due to incorrect byte length calculations in the Node.js Buffer API. The flaw is reachable over the network with no authentication required and no user interaction needed, making it exploitable against any Electron-based desktop application that processes external input. Successful exploitation causes the affected application to crash and may allow incorrect buffer allocations leading to memory corruption, data truncation, or arbitrary code execution. No fix version has been published upstream yet; HarborGuard tracks this advisory and will make a patched-image rebuild available the moment an upstream fix is released.

HarborGuard Coverage

Exploit Conditions

• Network reachabilityRequired

  The vulnerable code path is exposed over the network, meaning an attacker can send crafted input to the application from a remote host without requiring any foothold on the target system.

• AuthenticationNot required

  No credentials or prior authentication are needed to trigger the incorrect byte length calculation; the flaw can be reached by any unauthenticated party that can send input to the application.

• Victim interactionNot required

  Exploitation does not depend on a user clicking a link or performing any action; the attacker can trigger the vulnerability entirely without victim participation.

• Attack complexityDetail

  Attack complexity is low, meaning the exploit is reliable and requires no special environmental conditions, race conditions, or memory layout prerequisites to trigger the buffer miscalculation.

Blast Radius

• A successful attacker causes the Electron application to crash, making it unavailable to the end user (high availability impact against the vulnerable component).
• Incorrect buffer allocations allow the attacker to read memory contents outside intended boundaries, exposing in-memory data such as session tokens, credentials, or application state (high confidentiality impact).
• The buffer under/overflow enables writes to adjacent heap memory, allowing an attacker to corrupt application data or manipulate program logic in ways that alter persisted or in-flight data (high integrity impact).
• In the worst case, controlled heap corruption provides a path to arbitrary code execution within the Electron renderer or main process, giving the attacker full control of the application context.