{"id":"GHSA-pgpf-m8m4-6cg6","summary":"Winter vulnerable to privilege escalation by authenticated backend users","details":"## Impact\nAffected versions of Winter CMS allowed authenticated backend users to escalate their accounts level of access to the system by modifying the roles / permissions assigned to their account through specially crafted requests to the backend while logged in.\n\nTo actively exploit this security issue, an attacker would need access to the Backend with a user account with any level of access.\n\nThe Winter CMS maintainers strongly recommend that all Winter CMS sites that have any reliance on the roles & permissions system to update immediately. Security fixes have been backported to all major versions of Winter (1.0, 1.1, and 1.2).\n\n## Patches\nMultiple fixes and defence in depth has been applied to prevent current and future privilege escalation attacks at the lowest level possible.\n\nThis security issue has been fixed as of https://wintercms.com/releases/v1.0.477, https://wintercms.com/releases/v1.1.12, https://wintercms.com/releases/v1.2.12.\n\n## Workarounds\nIf you cannot upgrade, you may apply the changes from the releases to your Winter CMS installation manually to resolve this issue.","aliases":["CVE-2026-27591"],"modified":"2026-03-14T02:26:20.728290Z","published":"2026-03-12T14:07:39Z","database_specific":{"github_reviewed_at":"2026-03-12T14:07:39Z","nvd_published_at":"2026-03-11T22:16:32Z","cwe_ids":["CWE-284","CWE-639","CWE-915"],"severity":"CRITICAL","github_reviewed":true},"references":[{"type":"WEB","url":"https://github.com/wintercms/winter/security/advisories/GHSA-pgpf-m8m4-6cg6"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-27591"},{"type":"PACKAGE","url":"https://github.com/wintercms/winter"},{"type":"WEB","url":"https://wintercms.com/releases/v1.0.477"},{"type":"WEB","url":"https://wintercms.com/releases/v1.1.12"},{"type":"WEB","url":"https://wintercms.com/releases/v1.2.12"}],"affected":[{"package":{"name":"winter/wn-backend-module","ecosystem":"Packagist","purl":"pkg:composer/winter/wn-backend-module"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.2.0"},{"fixed":"1.2.12"}]}],"versions":["v1.2.0","v1.2.1","v1.2.10","v1.2.11","v1.2.2","v1.2.3","v1.2.4","v1.2.5","v1.2.6","v1.2.7","v1.2.8","v1.2.9"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-pgpf-m8m4-6cg6/GHSA-pgpf-m8m4-6cg6.json"}},{"package":{"name":"winter/wn-backend-module","ecosystem":"Packagist","purl":"pkg:composer/winter/wn-backend-module"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.1.0"},{"fixed":"1.1.12"}]}],"versions":["v1.1.10","v1.1.11","v1.1.2","v1.1.3","v1.1.4","v1.1.5","v1.1.6","v1.1.7","v1.1.8","v1.1.9"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-pgpf-m8m4-6cg6/GHSA-pgpf-m8m4-6cg6.json"}},{"package":{"name":"winter/wn-backend-module","ecosystem":"Packagist","purl":"pkg:composer/winter/wn-backend-module"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.0.477"}]}],"versions":["v1.0.473","v1.0.474","v1.0.475"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/03/GHSA-pgpf-m8m4-6cg6/GHSA-pgpf-m8m4-6cg6.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H"}]}