CVE-2026-23889 is a medium-severity path traversal vulnerability in pnpm (npm), affecting versions < 10.28.1. It is fixed in 10.28.1.
Summary A path traversal vulnerability in pnpm's tarball extraction allows malicious packages to write files outside the package directory on Windows. The path normalization only checks for ./ but not .\. On Windows, backslashes are directory separators, enabling path traversal. This vulnerability is Windows-only. Details Incomplete Path Normalization (store/cafs/src/parseTarball.ts:107-110) A path like foo\..\..\.npmrc does NOT contain ./ and bypasses this check. Platform-Dependent Behavior (fs/indexed-pkg-importer/src/importIndexedDir.ts:97-98) On Unix: Backslashes are literal filename characters (safe) On Windows: Backslashes are directory separators (exploitable) PoC Create a malicious tarball with entry package/foo\..\..\.npmrc Host it or use as a tarball URL dependency On Windows: pnpm install Observe .npmrc written outside package directory Impact Windows pnpm users Windows CI/CD pipelines (GitHub Actions Windows runners, Azure DevOps) Can overwrite .npmrc, build configs, or other files Verified on pnpm main @ commit 5a0ed1d45.
Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.
CVE-2026-23889 has a CVSS score of 6.5 (Medium). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment.
A fixed version is available (10.28.1). Upgrading removes the vulnerable code path.
npm
pnpm (< 10.28.1)pnpm → 10.28.1 (npm)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter instead of chasing every advisory.
Kodem's runtime-powered SCA identifies whether CVE-2026-23889 is reachable in your applications. Explore open-source security for your team.
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Already deployed Kodem? See CVE-2026-23889 in your environment →Upgrade pnpm to 10.28.1 or later to resolve this vulnerability.
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CVE-2026-23889 is a medium-severity path traversal vulnerability in pnpm (npm), affecting versions < 10.28.1. It is fixed in 10.28.1. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
CVE-2026-23889 has a CVSS score of 6.5 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
pnpm (npm) versions < 10.28.1 is affected.
Yes. CVE-2026-23889 is fixed in 10.28.1. Upgrade to this version or later.
Whether CVE-2026-23889 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
Upgrade pnpm to 10.28.1 or later.