CVE-2026-23890 is a medium-severity (CVSS 6.5) CWE-23 vulnerability in pnpm. A fix is available for pnpm — see the affected versions and patch details below.
pnpm scoped bin name Path Traversal allows arbitrary file creation outside node_modules/.bin
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-23890.
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-2026-23890 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 379,842 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
A path traversal vulnerability in pnpm's bin linking allows malicious npm packages to create executable shims or symlinks outside of node_modules/.bin. Bin names starting with @ bypass validation, and after scope normalization, path traversal sequences like ../../ remain intact.
Details
The vulnerability exists in the bin name validation and normalization logic:
1. Validation Bypass (pkg-manager/package-bins/src/index.ts)
The filter allows any bin name starting with @ to pass through without validation:
.filter((commandName) =>
encodeURIComponent(commandName) === commandName ||
commandName === '' ||
commandName[0] === '@' // <-- Bypasses validation
)
2. Incomplete Normalization (pkg-manager/package-bins/src/index.ts)
function normalizeBinName (name: string): string {
return name[0] === '@' ? name.slice(name.indexOf('/') + 1) : name
}
// Input: @scope/../../evil
// Output: ../../evil <-- Path traversal preserved!
3. Exploitation (pkg-manager/link-bins/src/index.ts:288)
The normalized name is used directly in path.join() without validation.
PoC
- Create a malicious package:
{
"name": "malicious-pkg",
"version": "1.0.0",
"bin": {
"@scope/../../.npmrc": "./malicious.js"
}
}
- Install the package:
pnpm add /path/to/malicious-pkg
- Observe
.npmrccreated in project root (outside node_modules/.bin).
Impact
- All pnpm users who install npm packages
- CI/CD pipelines using pnpm
- Can overwrite config files, scripts, or other sensitive files
Verified on pnpm main @ commit 5a0ed1d45.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | pnpm | all versions | 10.28.1npm install pnpm@10.28.1 |
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 10.28.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-23890 is resolved across your whole dependency graph.
Workarounds
Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-23890 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-23890. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This vulnerability is rated Moderate for Red Hat. It affects systems using pnpm where malicious npm packages can exploit a path traversal flaw during bin linking. This allows the creation of executable files or symlinks outside of the `node_modules/.bin` directory, posing a risk in environments that install untrusted…
To mitigate this issue, ensure that only trusted npm packages are installed when utilizing pnpm. Restrict the use of pnpm for package installation to controlled environments, such as secure CI/CD pipelines, to prevent the introduction of malicious packages. Implement robust package source validation and integrity checks to minimize exposure.Source: Red Hat security advisory for CVE-2026-23890 (CC BY 4.0)
Frequently Asked Questions
Is CVE-2026-23890 in your dependencies?
O3 Security finds CVE-2026-23890 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.