{"id":"CVE-2026-103503","summary":"Hex trusts its bundled CA certificates when cacerts_path is set","details":"Improper Certificate Validation vulnerability in hexpm hex allows an attacker who can intercept HTTPS connections, and holds a certificate for a Hex host issued by a CA in Hex's bundled CA store, to impersonate that host to users who set cacerts_path to a CA store that leaves that CA out.\n\ncacerts_path (HEX_CACERTS_PATH) is documented as the path to the CA certificate store, used instead of the CA bundle that ships with Hex. Hex.HTTP.SSL.ssl_opts/1 passes the configured store as the cacerts option, but builds the partial_chain callback from the bundled store whether cacerts_path is set or not. Hex.HTTP.SSL.partial_chain/2 accepts a server chain when any certificate in it has the same public key as a bundled CA certificate, so a chain that leads to a bundled CA passes verification although the configured store doesn't contain that CA. Hostname verification still applies.\n\nThis issue affects hex: from 0.20.2 before 2.5.2.","aliases":["EEF-CVE-2026-103503","GHSA-rw8q-hg7m-cxgr"],"modified":"2026-10-14T02:46:07.176534197Z","published":"2026-10-12T15:17:45.545Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/103xxx/CVE-2026-103503.json","unresolved_ranges":[{"extracted_events":[{"introduced":"0.20.2"},{"fixed":"2.5.2"}],"source":"AFFECTED_FIELD"}],"cna_assigner":"EEF","cwe_ids":["CWE-295"]},"references":[{"type":"WEB","url":"https://cna.erlef.org/cves/CVE-2026-103503.html"},{"type":"WEB","url":"https://github.com"},{"type":"WEB","url":"https://osv.dev/vulnerability/EEF-CVE-2026-103503"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/103xxx/CVE-2026-103503.json"},{"type":"ADVISORY","url":"https://github.com/hexpm/hex/security/advisories/GHSA-rw8q-hg7m-cxgr"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-103503"},{"type":"FIX","url":"https://github.com/hexpm/hex/commit/5f5a2136c7cf5991b6e8a30d645ca9f8e74b0785"},{"type":"FIX","url":"https://github.com/hexpm/hex/commit/6232a6498015e559743bec4f4fbec9138837cec8"},{"type":"FIX","url":"https://github.com/hexpm/hex/commit/c9b26a46928bfcd546773571e09c1d05f4cd9fb7"},{"type":"PACKAGE","url":"https://github.com/hexpm/hex"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/hexpm/hex","events":[{"introduced":"c9b26a46928bfcd546773571e09c1d05f4cd9fb7"},{"fixed":"5f5a2136c7cf5991b6e8a30d645ca9f8e74b0785"},{"fixed":"6232a6498015e559743bec4f4fbec9138837cec8"},{"fixed":"c9b26a46928bfcd546773571e09c1d05f4cd9fb7"}],"database_specific":{"source":"REFERENCES"}}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-103503.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:A/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N"}]}