Description
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.
References (1)
Core 1
Core References
X_Refsource_Confirm x_refsource_confirm
https://github.com/esm-dev/esm.sh/security/advisories/GHSA-3636-h3vx-6465
Scores
CVSS v4
8.7
EPSS
0.0036
EPSS Percentile
27.8%
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CISA SSVC
Vulnrichment
Exploitation
poc
Automatable
yes
Technical Impact
partial
Details
CWE
CWE-22
Status
published
Products (2)
esm-dev/esm.sh
0 - 0.0.0-20260508100112-1960055e1d53Go
esm-dev/esm.sh
<= 137
Published
May 28, 2026
Tracked Since
May 28, 2026