high

CVE-2026-55698

npm · pnpm

Summary

pnpm: Project env lockfile can short-circuit package-manager resolution and execute lockfile-selected pnpm bytes

Severity
high
CVSS
8.8
EPSS
0.3% (p22)
CWE
CWE-345, CWE-494, CWE-829
Also known as
GHSA-w466-c33r-3gjp
Published
2026-06-26
Updated
2026-06-26

Advisory details

Maintainer Action Plan

This report is ready to review with the shared patch branch. Start with the PR and the expected fixed behavior, then use the detailed exploit narrative below only if you want to replay the original path.

Expected Patched Behavior

Committed env-lockfile package-manager entries are force-refreshed through trusted registries before execution; attacker tarball requests and markers stay at zero.

Files And Tests To Review

Focused Validation

Run these from a checkout of the shared patch branch. They are the useful maintainer commands with machine-local artifact paths removed.

./node_modules/.bin/tsgo --build installing/env-installer/tsconfig.json
./node_modules/.bin/tsgo --build pnpm/tsconfig.json
PNPM_REGISTRY_MOCK_PORT=7799 NODE_OPTIONS="--experimental-vm-modules --disable-warning=ExperimentalWarning --disable-warning=DEP0169" ../node_modules/.bin/jest src/switchCliVersion.test.ts -t "re-resolved package-manager lockfile" --runInBand
PNPM_REGISTRY_MOCK_PORT=7799 NODE_OPTIONS="--experimental-vm-modules --disable-warning=ExperimentalWarning --disable-warning=DEP0169" ../node_modules/.bin/jest src/switchCliVersion.test.ts src/syncEnvLockfile.test.ts --runInBand
./node_modules/.bin/eslint installing/env-installer/src/resolvePackageManagerIntegrities.ts pnpm/src/switchCliVersion.ts pnpm/src/switchCliVersion.test.ts
git diff --check

The full patched replay for the shared branch passed with all 20 candidates marked fixed. This candidate's replay evidence is results/CAND-PNPM-063-patched-result.json.

Summary

pnpm can persist package-manager bootstrap metadata in the first YAML document of pnpm-lock.yaml. Before the patch, direct pnpm execution trusted an already resolved packageManagerDependencies entry when the committed env lockfile contained matching pnpm and @pnpm/exe versions. A malicious repository could therefore commit package-manager lockfile package records and snapshots that bypassed fresh package-manager resolution, then cause pnpm to install and execute bytes selected by that committed lockfile state during automatic version switching.

Details

The vulnerable source-to-sink path was:

The helper fast path is intentionally still version-based for non-execution callers, so the security boundary is enforced at the execution path: switchCliVersion() now re-resolves already present package-manager env-lockfile entries before they can reach installPnpmToStore() and spawn.sync().

PoC

Standalone PoC and verification script:

The PoC constructs a committed env-lockfile object with matching package-manager dependency versions and attacker-selected package metadata:

{
  "importers": {
    ".": {
      "configDependencies": {},
      "packageManagerDependencies": {
        "@pnpm/exe": { "specifier": "9.3.0", "version": "9.3.0" },
        "pnpm": { "specifier": "9.3.0", "version": "9.3.0" }
      }
    }
  },
  "lockfileVersion": "9.0",
  "packages": {
    "/pnpm@9.3.0": {
      "resolution": {
        "integrity": "sha512-poisoned"
      }
    }
  },
  "snapshots": {
    "/pnpm@9.3.0": {}
  }
}

Pre-patch exploit model:

  1. The victim runs pnpm directly in a malicious repository.
  2. The requested package-manager version differs from the currently running pnpm.
  3. pnpm enters switchCliVersion() and reads the committed env lockfile.
  4. Matching pnpm / @pnpm/exe versions short-circuit package-manager resolution.
  5. pnpm installs from the committed env-lockfile package records and executes the resulting pnpm binary.

Observed primitive proof from the PoC:

{
  "primitive": "unforced resolver reuses already-resolved env lockfile metadata",
  "isResolvedByVersionOnly": true,
  "reusedPoisonedIntegrity": true
}

The same script then runs the patched switchCliVersion regression. The regression seeds a poisoned committed env lockfile, has the resolver return a trusted replacement lockfile, and asserts installPnpmToStore() receives the trusted lockfile rather than the committed one. This would fail on the vulnerable control flow because the resolver was not called and the committed lockfile reached the installer.

Focused validation commands:

./node_modules/.bin/tsgo --build installing/env-installer/tsconfig.json
./node_modules/.bin/tsgo --build pnpm/tsconfig.json
PNPM_REGISTRY_MOCK_PORT=7799 NODE_OPTIONS="--experimental-vm-modules --disable-warning=ExperimentalWarning --disable-warning=DEP0169" ../node_modules/.bin/jest src/switchCliVersion.test.ts -t "re-resolved package-manager lockfile" --runInBand
PNPM_REGISTRY_MOCK_PORT=7799 NODE_OPTIONS="--experimental-vm-modules --disable-warning=ExperimentalWarning --disable-warning=DEP0169" ../node_modules/.bin/jest src/switchCliVersion.test.ts src/syncEnvLockfile.test.ts --runInBand
./node_modules/.bin/eslint installing/env-installer/src/resolvePackageManagerIntegrities.ts pnpm/src/switchCliVersion.ts pnpm/src/switchCliVersion.test.ts
git diff --check

Validation result:

Impact

A malicious repository can cause arbitrary package-manager code execution in the victim's developer or CI environment before normal command handling continues. That code executes with the victim user's privileges and can read loc

References

Related advisories

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Sources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.