TI-2025-36903 Aliases CVE-2025-59342 GHSA-g2h5-cvvr-7gmw

esm.sh writes arbitrary files via path traversal in `X-Zone-Id` header

MEDIUM 64CWE-24Published 2025-09-17 · Updated 2026-01-14

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Attack requirements: None
Impact type: —
Confidentiality · integrity · availability: None · Low · None
Fix status: Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub.

Summary

esm.sh is a nobuild content delivery network(CDN) for modern web development. In 136 and earlier, a path-traversal flaw in the handling of the X-Zone-Id HTTP header allows an attacker to cause the application to write files outside the intended storage location. The header value is used to build a filesystem path but is not properly canonicalized or restricted to the application’s storage base directory. As a result, supplying ../ sequences in X-Zone-Id causes files to be written to arbitrary directories. Version 136.1 contains a patch.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.03153 88th percentileScored 2026-11-07

Fix Fixed github.com/esm-dev/esm.sh (Go): 136.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
esm-dev	esm.sh	up to 136	—	No fix listed	CNA
—	github.com/esm-dev/esm.sh (Go)	before 136.1	136.1	Patch available	GHSA-g2h5-cvvr-7gmw

esm.sh Vendoresm-dev Affected up to 136 Fixed in — No fix listed CNA
github.com/esm-dev/esm.sh (Go) Vendor— Affected before 136.1 Fixed in 136.1 Patch available GHSA-g2h5-cvvr-7gmw

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:esm:esm.sh::::::::	—	—	esm-dev

cpe:2.3:a:esm:esm.sh:*:*:*:*:*:*:*:* Versions — — ·esm-dev

Remediation

Fix · GHSA-g2h5-cvvr-7gmw github.com/esm-dev/esm.sh (Go) Fixed in 136.1 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2025-59342
2026-10-03 Alias added: GHSA-g2h5-cvvr-7gmw

References

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2025-59342

Other 6

TI-2025-40211 esm.sh CDN service has arbitrary file write via tarslip CVSS 3.1CRITICAL 9.8
TI-2026-32504 esm.sh: Legacy Route Path Traversal Can Lead to RCE CVSS 4.0HIGH 8.7
TI-2025-32063 esm.sh is vulnerable to full-response SSRF CVSS 4.0HIGH 8.7
TI-2025-40212 esm.sh CDN service has JS Template Literal Injection in CSS-to-JavaScript CVSS 3.1CRITICAL 9.6
TI-2025-36902 Local File Inclusion in esm.sh CVSS 4.0HIGH 7.7
TI-2026-32505 esm.sh: Path Traversal via package.json browser field allows reading arbitrary server files CVSS 3.1HIGH 7.5

See all 9 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences