CVE-2026-27730
esm.sh is a no-build content delivery network (CDN) for web development.
Published Feb 25, 2026 · updated Jun 17, 2026 · esm esm.sh
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 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.
Code
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No public source repository is identified for this product.
Timeline
Detection, updates, and resolution for this record.
Feb 25, 2026 · NIST NVD
Detected
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 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 loc
Jun 17, 2026 · NIST NVD
Updated
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 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 loc
Affected
- cpe esm/esm.shversion unspecified
Sources
- CVE.orgVulnerability recordCVE-2026-27730
Official CVE identifier
cve.org - NIST NVDVulnerability recordCVE-2026-27730
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 fetch route. The service tries to block localhost/internal targets, but the validation is based on hostname string
nvd.nist.gov