{"id":"GHSA-p8p9-5953-h9jw","aliases":["CVE-2026-7886"],"title":"Concrete CMS is vulnerable to IDOR in AddMessage/UpdateMessage","titleSource":"OSV","descriptionSource":"OSV","declaredSeverity":"LOW","description":"Concrete CMS 9.5.0 and below is vulnerable to IDOR in AddMessage/UpdateMessage via attachments[] parameter which can lead to file permission bypass. The `AddMessage` and `UpdateMessage` conversation controllers accept user-supplied file attachment IDs and load files directly via `$em->find(File::class, $attachmentID)` without checking per-file permissions (`canViewFile()`). A user who can post in any conversation can reference any file in the CMS file manager by its sequential ID, effectively bypassing the file permission system. If a site truly has private files, the owner should set up a  private storage location https://documentation.concretecms.org/user-guide/editors-reference/dashboard/system-and-maintenance/files/file-storage-locations outside of the webroot so that permissions can be checked on view as well. That way, even if an authorized user attaches a file, or otherwise links to it, unauthorized users won't be able to view the file.","severity":"low","score":2.3,"published":"2026-05-22T00:31:16.000Z","modified":"2026-09-10T03:51:06.663Z","withdrawn":false,"knownExploited":false,"affected":[{"ecosystem":"Packagist","name":"concrete5/concrete5","sources":[{"name":"OSV · GHSA-p8p9-5953-h9jw","url":"https://osv.dev/vulnerability/GHSA-p8p9-5953-h9jw"}],"ranges":[{"events":[{"introduced":"0"},{"fixed":"9.5.1"}],"type":"ECOSYSTEM"}],"versions":["8.0","8.0.1","8.0.2","8.0.3","8.1.0","8.2.0","8.2.0RC2","8.2.1","8.3.0","8.3.1","8.3.2","8.4.0","8.4.0RC3","8.4.0RC4","8.4.1","8.4.2","8.4.3","8.4.4","8.4.5","8.5.0","8.5.0RC1","8.5.0RC2","8.5.1","8.5.10","8.5.11","8.5.12","8.5.13","8.5.14","8.5.15","8.5.16","8.5.17","8.5.18","8.5.19","8.5.2","8.5.20","8.5.21","8.5.3","8.5.4","8.5.5","8.5.6","8.5.6RC1","8.5.7","8.5.8","8.5.9","9.0.0","9.0.0RC1","9.0.0RC3","9.0.0RC4","9.0.1","9.0.2","9.1.0","9.1.1","9.1.2","9.1.3","9.2.0","9.2.0RC2","9.2.1","9.2.2","9.2.3","9.2.4","9.2.5","9.2.6","9.2.7","9.2.8","9.2.9","9.3.0","9.3.1","9.3.2","9.3.3","9.3.4","9.3.5","9.3.6","9.3.7","9.3.8","9.3.9","9.4.0","9.4.0RC1","9.4.0RC2","9.4.1","9.4.2","9.4.3","9.4.4","9.4.5","9.4.6","9.4.7","9.4.8","9.5.0","9.5.0RC1","9.5.0RC2"],"fixed":["9.5.1"]}],"sourceAffected":[],"references":["https://nvd.nist.gov/vuln/detail/CVE-2026-7886","https://documentation.concretecms.org/9-x/developers/introduction/version-history/951-release-notes","https://github.com/concretecms/concretecms"],"sources":[{"name":"OSV","id":"GHSA-p8p9-5953-h9jw","modified":"2026-09-10T03:51:06.663290725Z","url":"https://osv.dev/vulnerability/GHSA-p8p9-5953-h9jw"}],"assessments":[{"source":"OSV","vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N","score":2.3}],"products":[],"remediation":[],"kev":{"status":"not-listed","checkedAt":"2026-10-29T00:35:31.531Z"},"coverage":[{"source":"NVD","status":"not-checked"},{"source":"GHSA","status":"not-checked"},{"source":"EUVD","status":"not-checked"},{"source":"EPSS","status":"not-checked"}],"evidence":[]}