CVE-2026-55700 is a high-severity (CVSS 7.1) Path Traversal vulnerability in pnpm. A fix is available for pnpm — see the affected versions and patch details below.
pnpm: stage download writes outside destination via manifest version traversal
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-55700.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-55700 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
pnpmnpmDescription
Summary
The staged-tarball filename traversal reported as GHSA-v23m-ccfg-pq9h / CAND-PNPM-038 is fixed on main by pnpm/pnpm#12303, merged as 65443f4bdf1f0db9c8c7dc58fee25252607e9234.
Before the fix, 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.
Security boundary
- Package names and semantic versions are validated before they can influence a local filename.
- POSIX and Windows path separators are rejected by basename checks.
- Stage download and tarball summary paths use the same filename helper.
- The resolved output path must remain an immediate child of the selected download directory.
- The stage identifier is already constrained to a UUID.
Exploit replay
Before 65443f4bdf, a traversal-bearing manifest version could make the command write outside the selected directory. After the fix, malicious package names fail with ERR_PNPM_INVALID_PACKAGE_NAME, malicious versions fail with ERR_PNPM_INVALID_PACKAGE_VERSION, no outside file is created, and the download directory remains empty.
Files changed
releasing/commands/src/tarball/safeTarballFilename.tsvalidates manifest identity and rejects cross-platform path separators.releasing/commands/src/stage/download.tsverifies the resolved destination before writing.releasing/commands/src/tarball/summarizeTarball.tsuses the same filename contract.releasing/commands/test/stage.test.tscovers traversal through both package name and version..changeset/stale-stage-tarballs.mdincludes patch bumps for@pnpm/releasing.commandsandpnpm.
Patch
- Merged PR: https://github.com/pnpm/pnpm/pull/12303
- Fix commit:
65443f4bdf1f0db9c8c7dc58fee25252607e9234 - The private candidate branch was not submitted because it conflicts with and is superseded by the merged fix. The upstream patch is slightly stronger because it covers malicious package names as well as versions.
Commands run
$ git diff --check 65443f4bdf^ 65443f4bdf
PASS
$ gh pr view 12303 --repo pnpm/pnpm --json state,mergeCommit,statusCheckRollup
MERGED as 65443f4bdf
Validation
- Upstream regression coverage rejects traversal through both manifest name and version and verifies that no outside file is created.
- Compile and lint, dependency audit, Linux Node.js 22/24/26, CodeQL, and zizmor checks passed on the merged public PR.
- The Windows Node.js 22 full-suite job timed out in the unrelated
pnpm/test/dlx.tscache test after 512 other tests passed. The PR was merged by the maintainer; the failure did not involve the staging code. - The earlier private candidate's focused exploit regression, positive control, package compile, ESLint, and
git diff --checkalso passed.
Compatibility
Staging and release commands are TypeScript-only. Pacquet does not expose this command family, so no Rust-side port is required.
Remaining risk
The final fs.writeFile follows a pre-existing symlink at the exact in-directory output name. That requires separate local filesystem access and is not controllable through the registry manifest traversal described here.
Written by an agent (Codex, GPT-5).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | pnpm | ≥ 11.3.0&&< 11.5.3 | 11.5.3npm install pnpm@11.5.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pnpm, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update pnpm to 11.5.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-55700 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-55700 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-55700. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-55700 in your dependencies?
O3 Security finds CVE-2026-55700 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.