{"id":"CVE-2019-15794","url":"https://www.cyber-defence.io/tools/cve/CVE-2019-15794","generatedAt":"2026-10-28T21:31:48.026Z","title":"Overlayfs in the Linux kernel and shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, both replace vma->vm_file in their mmap handlers.","description":"Overlayfs in the Linux kernel and shiftfs, a non-upstream patch to the Linux kernel included in the Ubuntu 5.0 and 5.3 kernel series, both replace vma->vm_file in their mmap handlers. On error the original value is not restored, and the reference is put for the file to which vm_file points. On upstream kernels this is not an issue, as no callers dereference vm_file following after call_mmap() returns an error. However, the aufs patchs change mmap_region() to replace the fput() using a local variable with vma_fput(), which will fput() vm_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":6.7,"severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-672"],"affected":["linux/linux kernel","canonical/ubuntu linux"],"epss":{"score":0.01158,"percentile":0.66934,"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":47692,"kind":"exploit","title":"Ubuntu 19.10 - ubuntu-aufs-modified mmap_region() Breaks Refcounting in overlayfs/shiftfs Error Path","url":"https://www.exploit-db.com/exploits/47692","sourceUrl":"https://gitlab.com/exploit-database/exploitdb/-/blob/main/exploits/linux/dos/47692.txt","file":"exploits/linux/dos/47692.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-2019-15794"],"tags":null,"aliases":null,"applicationUrl":null,"screenshotUrl":null,"referenceUrl":"https://bugs.chromium.org/p/project-zero/issues/detail?id=1958"}]},"verdict":{"level":"high","text":"A public exploit is published in Exploit-DB (verified), so the technical barrier is gone even though the severity is medium and EPSS is 1.2%. Treat it as high on anything reachable from the internet."},"changes":[],"references":[{"url":"https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/eoan/commit/?id=270d16ae48a4dbf1c7e25e94cc3e38b4bea37635","tags":["Mailing List","Patch","Third Party Advisory"],"source":"security@ubuntu.com"},{"url":"https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/eoan/commit/?id=ef81780548d20a786cc77ed4203fca146fd81ce3","tags":["Mailing List","Patch","Third Party Advisory"],"source":"security@ubuntu.com"},{"url":"https://usn.ubuntu.com/usn/usn-4208-1","tags":["Third Party Advisory"],"source":"security@ubuntu.com"},{"url":"https://usn.ubuntu.com/usn/usn-4209-1","tags":["Third Party Advisory"],"source":"security@ubuntu.com"},{"url":"https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/eoan/commit/?id=270d16ae48a4dbf1c7e25e94cc3e38b4bea37635","tags":["Mailing List","Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/eoan/commit/?id=ef81780548d20a786cc77ed4203fca146fd81ce3","tags":["Mailing List","Patch","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://usn.ubuntu.com/usn/usn-4208-1","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://usn.ubuntu.com/usn/usn-4209-1","tags":["Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2019-15794","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."}