Unauthenticated file writes via absolute tar paths
Published Jan 18, 2026 · Updated Jan 18, 2026
Path traversal in esm.sh before 0.0.0-20260116051925-c62ab83c589e allows remote attackers to write files via malicious package tarballs. The extractPackageTarball function strips the tar root, applies path.Clean, and joins an absolute member name to the package directory without confining the result. A reachable service must fetch an attacker-controlled package; writes are limited by allowed extensions and service-account permissions, enabling configuration overwrite or cache poisoning.
Summary
What happened
Path traversal in esm.sh before 0.0.0-20260116051925-c62ab83c589e allows remote attackers to write files via malicious package tarballs. The extractPackageTarball function strips the tar root, applies path.Clean, and joins an absolute member name to the package directory without confining the result. A reachable service must fetch an attacker-controlled package; writes are limited by allowed extensions and service-account permissions, enabling configuration overwrite or cache poisoning.
The record
- CVE
- CVE-2026-23644
- Published
- Jan 18, 2026
- Updated
- Jan 18, 2026
- Vendor
- esm-dev
- Product
- esm.sh
- Classifications
- CWE-22, T1190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jan 18, 2026CVE publishedPublication date reported by the CVE source.
- Jan 18, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 0.0.0-20260116051925-c62ab83c589e
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GHSA-2657-3c98-63jq extractPackageTarball proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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