{"id":"CVE-2026-75592","title":"Kirby is an open-source content management system","summary":"Kirby is an open-source content management system. Prior to 4.9.5 and 5.5.2, depending on the release line, Kirby's media handler used incomplete filesystem containment checks in src/Filesystem/Dir.php and src/Filesystem/F.php through Ki…","severity":"medium","cwe":["CWE-22"],"vendor":"getkirby","product":"getkirby/cms","affected":["getkirby/cms < 4.9.5","getkirby/cms >= 5.0.0, < 5.5.2"],"patched":["getkirby/cms 4.9.5","getkirby/cms 5.5.2"],"published":"2026-08-31","updated":"2026-09-08","sourceUpdated":"2026-09-08T21:11:31.703","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-75592","references":[{"url":"https://github.com/getkirby/kirby/commit/2b6fab950bc89d505ea89576bf71c8de614cc3b2","label":"security-advisories@github.com"},{"url":"https://github.com/getkirby/kirby/commit/e0dca5f709adc21b36f5549df2c0619bc59da56c","label":"security-advisories@github.com"},{"url":"https://github.com/getkirby/kirby/releases/tag/4.9.5","label":"security-advisories@github.com"},{"url":"https://github.com/getkirby/kirby/releases/tag/5.5.2","label":"security-advisories@github.com"},{"url":"https://github.com/getkirby/kirby/security/advisories/GHSA-6j4c-mgqr-qv76","label":"security-advisories@github.com"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-75592"},{"url":"https://github.com/advisories/GHSA-6j4c-mgqr-qv76"}],"tags":["nvd","ghsa","composer"],"epss":0.00461,"epssPercentile":0.3911,"aliases":["GHSA-6j4c-mgqr-qv76"],"ecosystem":"composer","ingestedAt":"2026-09-02T15:46:29.826Z","slug":"CVE-2026-75592","body":"## Overview\n\nKirby is an open-source content management system. Prior to 4.9.5 and 5.5.2, depending on the release line, Kirby's media handler used incomplete filesystem containment checks in src/Filesystem/Dir.php and src/Filesystem/F.php through Kirby\\Filesystem\\Dir::realpath() and Kirby\\Filesystem\\F::realpath(). The checks accepted a sibling directory whose path shared the intended root's string prefix, such as /var/www/site2 next to /var/www/site, because they did not require an exact match or a DIRECTORY_SEPARATOR boundary. A remote attacker could use Kirby\\Cms\\Media::thumb() to create and access thumbnails from image files in a PHP-readable sibling directory when that directory contained a valid .json thumbnail job file, potentially exposing staging sites, backups, or other internal sites and deleting the job file during processing. This issue is fixed in versions 4.9.5 and 5.5.2.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.\n\n## Package advisory (CVE-2026-75592)\n\nAffected packages:\n\n- `getkirby/cms < 4.9.5`\n- `getkirby/cms >= 5.0.0, < 5.5.2`\n\nPatched in:\n\n- `getkirby/cms 4.9.5`\n- `getkirby/cms 5.5.2`\n\nSource: https://github.com/advisories/GHSA-6j4c-mgqr-qv76","depth":"sunlit","depthScore":28,"depthScoreParts":{"impact":27.5,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}