esm.sh is a no-build content delivery network (CDN) for web development. Versions up to and including 137 have an SSRF vulnerability (CWE-918) in esm.sh’s `/http(s)` fetch route. The service tries to block localhost/internal targets, but the validation is based on hostname string checks and can be bypassed using DNS alias domains. This allows an external requester to make the esm.sh server fetch internal localhost services. As of time of publication, no known patched versions exist.
Metrics
Affected Vendors & Products
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References
History
Wed, 25 Feb 2026 16:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | esm.sh is a no-build content delivery network (CDN) for web development. Versions up to and including 137 have an SSRF vulnerability (CWE-918) in esm.sh’s `/http(s)` fetch route. The service tries to block localhost/internal targets, but the validation is based on hostname string checks and can be bypassed using DNS alias domains. This allows an external requester to make the esm.sh server fetch internal localhost services. As of time of publication, no known patched versions exist. | |
| Title | esm.sh has SSRF localhost/private-network bypass in `/http(s)` module route | |
| Weaknesses | CWE-918 | |
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| Metrics |
cvssV3_0
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MITRE
Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-02-25T15:37:01.753Z
Reserved: 2026-02-23T18:37:14.789Z
Link: CVE-2026-27730
Vulnrichment
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NVD
Status : Received
Published: 2026-02-25T16:23:27.123
Modified: 2026-02-25T16:23:27.123
Link: CVE-2026-27730
Redhat
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OpenCVE Enrichment
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