CVE-2025-59342

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

MEDIUM
5.5
CVSS Score
Published: September 17, 2025 at 05:59 PM UTC
Updated: June 17, 2026 at 09:45 AM UTC
1 product affected across 1 vendorEsm.sh

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Severity
MEDIUM5.5
Exploit prediction
EPSS 3%
SSVC
PoC

Description

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

<= 136

Remediation

No guide yet

No remediation guidance has been written for this CVE yet, and no fixed version or vendor advisory is recorded against it.

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.5MEDIUMGitHub_M
Vector?

Quick Info

StatusDEFERRED
CWE
CWE-24

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