Vulnerability · Published Jan 18, 2026 · Assigned by GitHub_M

CVE-2026-23644esm.sh has path traversal in `extractPackageTarball` that enables file writes from malicious packages

High 7.7

In plain English

A high-severity path traversal in esm.sh from esm-dev. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 47% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)7.7High

Exploit odds (30 days)0.6%top 53.2% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

esm.sh is a no-build content delivery network (CDN) for web development. Prior to Go pseeudoversion 0.0.0-20260116051925-c62ab83c589e, the software has a path traversal vulnerability due to an incomplete fix. `path.Clean` normalizes a path but does not prevent absolute paths in a malicious tar file. Commit https://github.com/esm-dev/esm.sh/commit/9d77b88c320733ff6689d938d85d246a3af9af16, corresponding to pseudoversion 0.0.0-20260116051925-c62ab83c589e, fixes this issue.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
Go	github.com/esm-dev/esm.sh	no fix listed	GHSA-2657-3c98-63jq
Go	github.com/esm-dev/esm.sh	0.0.0-20260116051925-c62ab83c589e	GHSA-2657-3c98-63jq
Go	github.com/esm-dev/esm.sh	0.0.0-20260116051925-c62ab83c589e	GO-2026-4332

Affected products (as reported)

Vendor	Product	Versions
esm-dev	esm.sh	< 0.0.0-20260116051925-c62ab83c589e

Weakness: CWE-22 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:P

References

https://github.com/esm-dev/esm.sh/security/advisories/GHSA-2657-3c98-63jq x_refsource_CONFIRM
https://github.com/esm-dev/esm.sh/commit/9d77b88c320733ff6689d938d85d246a3af9af16 x_refsource_MISC
https://github.com/esm-dev/esm.sh/commit/c62ab83c589e7b421a0e1376d2a00a4e48161093 x_refsource_MISC
https://pkg.go.dev/vuln/GO-2025-4138 x_refsource_MISC