{"cve":"CVE-2026-27730","nvd":{"published":"2026-02-25T16:23:27.123","modified":"2026-06-17T10:27:34.187","status":"Analyzed","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N","score":7.5},"cwes":["CWE-918"],"references":["https://github.com/esm-dev/esm.sh/security/advisories/GHSA-p2v6-84h2-5x4r"],"products":["esm:esm.sh"],"source":"nvd","synced_at":"2026-10-19T22:24:17.937441719+00:00"},"epss":{"cve":"CVE-2026-27730","score":0.00386,"percentile":0.32723,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-p2v6-84h2-5x4r","url":"https://osv.dev/vulnerability/GHSA-p2v6-84h2-5x4r","summary":"esm.sh has SSRF localhost/private-network bypass in `/http(s)` module route","modified":"2026-03-09T02:03:39.631999354Z","packages":[{"ecosystem":"Go","name":"github.com/esm-dev/esm.sh","purl":"pkg:golang/github.com/esm-dev/esm.sh","ranges":["<0.0.0-20250616164159-0593516c4cfa"],"fixed":["0.0.0-20250616164159-0593516c4cfa"]}]},{"id":"GO-2026-4554","url":"https://osv.dev/vulnerability/GO-2026-4554","summary":"esm.sh has SSRF localhost/private-network bypass in `/http(s)` module route in github.com/esm-dev/esm.sh","modified":"2026-03-09T02:03:39.631999Z","packages":[{"ecosystem":"Go","name":"github.com/esm-dev/esm.sh","purl":"pkg:golang/github.com/esm-dev/esm.sh","ranges":["<0.0.0-20250616164159-0593516c4cfa"],"fixed":["0.0.0-20250616164159-0593516c4cfa"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}