CVE-2026-44593: high-severity vulnerability in esm-dev esm.sh
esm.sh: Legacy Route Path Traversal Can Lead to RCE
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.7epss 0.4%
esm.sh is a no-build content delivery network (CDN) for web development. In 137 and earlier, the legacy router first retrieves a response from legacyServer, parses the incoming request path, and ultimately writes the data to storage via buildStorage.Put. The router concatenates the path components without sanitizing them, producing a storage key. When this key is used, the underlying file system resolves the relative segments and writes the file to the specified path. Thus an attacker can craft a request that writes data to arbitrary locations on the server.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Affected products
esm-dev · esm.shRelated CVEs — esm-dev esm.sh
In the same product, most dangerous first.
CVE-2025-59342MEDIUMesm.sh writes arbitrary files via path traversal in `X-Zone-Id` headerEPSS 3.2%CVE-2025-59341HIGHLocal File Inclusion in esm.shEPSS 1.6%CVE-2026-102657HIGHesm.sh: web.NewHandler allows arbitrary file read via encoded dot-segment path traversalEPSS 0.7%CVE-2025-65025HIGHesm.sh CDN service has arbitrary file write via tarslipEPSS 0.6%CVE-2026-23644HIGHesm.sh has path traversal in `extractPackageTarball` that enables file writes from malicious packagesEPSS 0.6%CVE-2025-65026MEDIUMesm.sh CDN service has JS Template Literal Injection in CSS-to-JavaScriptEPSS 0.5%