{"action":"Upgrade craftcms/cms to 4.18 or later.","affected":[{"fixed":"5.10","introduced":"5.0.0-RC1"},{"fixed":"4.18","introduced":"4.0.0-RC1"}],"component":"craftcms/cms","cve_ids":["CVE-2026-55791"],"ecosystem":"Packagist","epss":0.00464,"exploited":false,"fixed_versions":["5.10","4.18"],"ghsa_id":"GHSA-c55v-343g-5xff","id":"tcs_01M5KF0KRZ3SGTHWKHK0FEEWC1","modified_at":"2026-09-10T03:51:08.401066886Z","published_at":"2026-06-19T21:15:19Z","references":["https://osv.dev/vulnerability/GHSA-c55v-343g-5xff","https://github.com/craftcms/cms/security/advisories/GHSA-c55v-343g-5xff","https://github.com/craftcms/cms/pull/18559","https://github.com/craftcms/cms"],"severity":{"label":"medium","score":6.9},"sources":[{"source":"osv","source_id":"GHSA-c55v-343g-5xff","url":"https://osv.dev/vulnerability/GHSA-c55v-343g-5xff"},{"source":"nvd","source_id":"CVE-2026-55791","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55791"}],"summary":"Craft CMS: Blind SSRF and Arbitrary JavaScript Injection via Host Header Poisoning in actionResourceJs"}