CVE-2026-44593 json
esm.sh: Legacy Route Path Traversal Can Lead to RCE
published 2026-05-12 5 mo ago modified 2026-10-26 13 d ago also GHSA-3636-h3vx-6465 , GO-2026-5071 , EUVD-2026-32910
- cvss
- 8.7
- version 4.0, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 38%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- go github.com/esm-dev/esm.sh 0.0.0-20260508100112-1960055e1d53
- govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1
opensuse advisories openSUSE-SU-2026:21483-1
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- yes
- Technical impact
- partial
- Assessed
- 5 mo ago
Exploit prediction
0.44% chance of exploitation in the next 30 days, higher than 38% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/esm-dev/esm.sh/security/advisories/GHSA-3636-h3vx-6465 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 8.7 | 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 |
| CNA | 4.0 | 8.7 | 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 |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| go | github.com/esm-dev/esm.sh | <0.0.0-20260508100112-1960055e1d53 |
0.0.0-20260508100112-1960055e1d53 |
Affected products
- esm-dev esm.sh
Classification
- Weakness
-
- CWE-22 Improper Limitation of a Pathname to a Restricted Directory
References
-
github.com
/esm-dev/esm.sh/security/advisories/GHSA-3636-h3vx-6465
exploit, web, advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-44593
advisory
-
github.com
/esm-dev/esm.sh
package
-
github.com
/esm-dev/esm.sh/releases/tag/v137_3
web
Sources
- CVE List CVE-2026-44593
- GitHub Advisory GHSA-3636-h3vx-6465
- NVD CVE-2026-44593
- OSV GO-2026-5071
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.