PGV-2664633 - pnpm: pacquet trust-lockfile install can create dependency symlinks outside the project

Disclosed on September 01, 2026 (updated September 01, 2026)

Vulnerability Overview

PGV-2664633 is a category 2 vulnerabilty that affects pnpm, versions ≥ 12.0.0-alpha.0 & < 12.0.0-alpha.5

CVSS Score: 7.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:L)

Risk Assessment

The risk assessment shows that this vulnerability is exlpoited by a compromised user. A legitimate user who unknowingly triggers exploitation of this vulnerability through normal interaction.

The impact is contained to the application. Exploitation remains confined to the application and cannot affect the host environment or external systems.

The threat damage is caused by a denial of service (limited). Exploitation can degrade or intermittently disrupt application availability without causing a full outage.is caused by data tampering. Exploitation can result in modification of any data (authorized or not) within the system.

Vulnerability Details

Summary

A crafted lockfile alias could reach several install-time filesystem joins. With --trust-lockfile or a frozen lockfile, traversal segments could create links outside the intended project or node_modules boundary. This patch validates dependency names and every virtual-store slot before creating directories, links, bins, or hoisted entries.

Security boundary

A shared safe-join helper rejects traversal, absolute, platform-specific, and reserved dependency names before filesystem materialization.
Direct and transitive dependency links, package links, bin destinations, and public/private hoist destinations use the same containment rule.
Global virtual-store slots validate the complete slot path, including version-derived components, before directory creation.
Snapshot slots and package names are checked before store initialization and before the current-lockfile fast path, closing the warm-install bypass.
Rejections preserve ERR_PNPM_INVALID_DEPENDENCY_NAME.

Exploit replay

Before the patch, pacquet install --frozen-lockfile --trust-lockfile accepted a ../../escaped-link dependency key and created a symlink outside the project. With this patch, the same lockfile is rejected before materialization and no outside link is created.

Files changed

pacquet/crates/package-manager/src/safe_join_modules_dir.rs defines the shared containment rule.
Install, symlink, bin, hoist, virtual-store, and frozen-lockfile paths call that helper before filesystem materialization.
The corresponding tests.rs files cover every sink, including warm installs and global virtual-store slots.

Commands run

$ cargo test --locked -p pacquet-package-manager --lib
PASS: 434 tests
$ cargo clippy --locked -p pacquet-package-manager --all-targets -- --deny warnings
PASS
$ cargo fmt --all -- --check
PASS

Validation

Full pacquet package-manager suite: 434 passed.
Focused regressions cover direct and transitive aliases, bins, hoists, package names, global virtual-store version traversal, and a poisoned prior-install slot.
cargo clippy -p pacquet-package-manager --all-targets -- -D warnings: passed.
cargo fmt --all -- --check and git diff --check: passed.

Compatibility

Valid unscoped and scoped dependency aliases continue to work. The reproduced escape was specific to pacquet, so this branch does not change the TypeScript CLI or the lockfile format.

Written by an agent (Codex, GPT-5).

Common Weakness Enumerations

CWE-22 - Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-59 - Improper Link Resolution Before File Access ('Link Following')
CWE-73 - External Control of File Name or Path

Additional References

Your Risk Profile

Network Exposure	External Accessable from the public internet
Access Interface	WebBrowser Primarily web-based applications
Service Outage	Disruptive Operations would be impacted
Data Breach	Disruptive Operations would be impacted
Data Tampering	Disruptive Operations would be impacted
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Additional Identifiers

GHSA-2rx9-3g3h-c2jv