{"schemaVersion":3,"id":"CVE-2026-96808","aliases":["UBUNTU-CVE-2026-96808","DEBIAN-CVE-2026-96808"],"status":"published","duplicateOf":null,"title":null,"description":"In Flatpak before 1.18.1, the revokefs writer, used by the flatpak-system-helper to receive repository data from unprivileged callers, validated file paths by rejecting literal .. components but did not prevent symlink traversal. A malicious local user in an active local session could obtain two revokefs sessions via the system helper, create a symlink in one session pointing into the other session's directory, and retain a file descriptor through that symlink. This allowed the attacker to modify files belonging to a different revokefs session after they had been validated and imported by the system helper. In particular, an attacker could use this to tamper with ostree commit objects in the system repository after they passed signature verification, enabling root-controlled file writes to attacker-chosen paths and local root privilege escalation.","dates":{"published":"2026-09-23T16:58:37.139Z","modified":"2026-09-23T18:22:46.208Z","reserved":null,"kevAdded":[],"kevDue":[]},"cvss":{"headline":{"score":7.4,"severity":"high","version":"3.1","versionLabel":"v3.1","source":"CVE.org","vector":"CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","computed":false,"selection":"backend-summary"},"metrics":[{"version":"3.1","versionLabel":"v3.1","source":"CVE.org","score":7.4,"severity":"high","vector":"CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","exploitability":null,"impact":null,"computed":false},{"version":"3.1","versionLabel":"v3.1","source":"OSV · 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This could allow an attacker to cause the product to operate on unauthorized files.","type":"weakness","status":"Incomplete","abstraction":"Compound","likelihoodOfExploit":"High","url":"https://cwe.mitre.org/data/definitions/61.html"}],"affected":[{"vendor":"debian","product":"flatpak","name":"flatpak","label":"flatpak","ecosystem":"Debian","cpePart":null,"purl":"pkg:deb/debian/flatpak","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null},{"text":"< 1.16.6-1~deb13u2","noFixRecorded":false,"fixedIn":null},{"text":"< 1.18.1-1","noFixRecorded":false,"fixedIn":null}],"versionsText":"All versions (No fix recorded) | < 1.16.6-1~deb13u2 | < 1.18.1-1","eol":null,"hubHref":null},{"vendor":"ubuntu","product":"flatpak","name":"flatpak","label":"flatpak","ecosystem":"Ubuntu","cpePart":null,"purl":"pkg:deb/ubuntu/flatpak","purlType":"deb","versions":[{"text":"All versions","noFixRecorded":true,"fixedIn":null}],"versionsText":"All versions (No fix recorded)","eol":null,"hubHref":null},{"vendor":"flatpak","product":"flatpak","name":"flatpak","label":"flatpak","ecosystem":null,"cpePart":"a","purl":null,"purlType":null,"versions":[{"text":"< 1.18.1","noFixRecorded":false,"fixedIn":null}],"versionsText":"< 1.18.1","eol":null,"hubHref":"/vendor/flatpak/flatpak"}],"affectedCount":3,"eol":{"hasEol":false,"count":0},"references":[{"url":"https://github.com/flatpak/flatpak/security/advisories/GHSA-qrwq-7qwx-q9rp","label":"github.com/flatpak/flatpak/security/advisories/GHSA-qrwq-7qwx-q9rp","hostname":"github.com","tags":["REPORT"]},{"url":"https://ubuntu.com/security/CVE-2026-96808","label":"ubuntu.com/security/CVE-2026-96808","hostname":"ubuntu.com","tags":["REPORT"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-96808","label":"www.cve.org/CVERecord?id=CVE-2026-96808","hostname":"www.cve.org","tags":["REPORT"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-96808","label":"security-tracker.debian.org/tracker/CVE-2026-96808","hostname":"security-tracker.debian.org","tags":["Advisory"]}],"lineage":{"upstream":[],"downstream":["RHSA-2026:80497","RHSA-2026:80498","RHSA-2026:80687","SUSE-SU-2026:4610-1"],"duplicates":[],"related":["SUSE-SU-2026:4610-1"]},"timeline":[{"kind":"published","date":"2026-09-23T16:58:37.139Z","label":"Published","detail":"Vulnerability first disclosed.","source":null},{"kind":"modified","date":"2026-09-23T18:22:46.208Z","label":"Last modified","detail":"Vulnerability information updated.","source":null}],"risk":{"score":30,"level":"medium","profile":"Default","thresholds":{"critical":75,"high":50,"medium":25,"low":10}},"meta":{"dataAsOf":"2026-10-21T22:03:04.303Z","stale":false,"partial":false}}