{"id":"CVE-2019-15791","url":"https://www.cyber-defence.io/tools/cve/CVE-2019-15791","generatedAt":"2026-10-28T22:21:53.943Z","title":"In shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, shiftfs_btrfs_ioctl_fd_replace() installs an fd referencing a file from the lower filesystem without taking an additional reference to that file.","description":"In shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, shiftfs_btrfs_ioctl_fd_replace() installs an fd referencing a file from the lower filesystem without taking an additional reference to that file. After the btrfs ioctl completes this fd is closed, which then puts a reference to that file, leading to a refcount underflow.","published":"2020-04-24T00:15:12.000Z","lastModified":"2026-06-17T02:21:05.000Z","status":"Modified","sourceIdentifier":"security@ubuntu.com","cvss":{"version":"3.1","score":7.8,"severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-672","CWE-191"],"affected":["linux/linux kernel","canonical/ubuntu linux"],"epss":{"score":0.01317,"percentile":0.70624,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":1,"verified":true,"firstPublished":"2019-11-20","source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[{"edbId":47693,"kind":"exploit","title":"Ubuntu 19.10 - Refcount Underflow and Type Confusion in shiftfs","url":"https://www.exploit-db.com/exploits/47693","sourceUrl":"https://gitlab.com/exploit-database/exploitdb/-/blob/main/exploits/linux/dos/47693.txt","file":"exploits/linux/dos/47693.txt","published":"2019-11-20","added":"2019-11-20","updated":"2019-11-20","author":"Google Security Research","type":"dos","platform":"linux","port":null,"verified":true,"codes":["CVE-2019-15793","CVE-2019-15792","CVE-2019-15791"],"tags":"Type Confusion","aliases":null,"applicationUrl":null,"screenshotUrl":null,"referenceUrl":"https://bugs.chromium.org/p/project-zero/issues/detail?id=1957"}]},"verdict":{"level":"urgent","text":"A public exploit is published in Exploit-DB (verified) and the impact is high, while EPSS rates exploitation at 1.3%. Anyone can run this; patch or mitigate before the next change window and check exposed instances for signs of use."},"changes":[],"references":[{"url":"https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/eoan/commit/?id=601a64857b3d7040ca15c39c929e6b9db3373ec1","tags":["Mailing List","Patch","Third Party Advisory"],"source":"security@ubuntu.com"},{"url":"https://usn.ubuntu.com/usn/usn-4183-1","tags":["Third Party Advisory"],"source":"security@ubuntu.com"},{"url":"https://usn.ubuntu.com/usn/usn-4184-1","tags":["Third Party Advisory"],"source":"security@ubuntu.com"},{"url":"https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/eoan/commit/?id=601a64857b3d7040ca15c39c929e6b9db3373ec1","tags":["Mailing List","Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://usn.ubuntu.com/usn/usn-4183-1","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://usn.ubuntu.com/usn/usn-4184-1","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2019-15791","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}