---
cve: "CVE-2019-15794"
severity: "HIGH"
cvss: 7.1
epss: "1.2%"
vendor: "Ubuntu"
kev: false
exploited: false
published: "2020-04-24 00:15:11"
tags: [cve, security, high]
source: tsecurity.de CVE-Dossier
exported: "2026-09-15T22:48:31+02:00"
---

# CVE-2019-15794

> 7.1 HIGH

## Beschreibung

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.

## CVSS-Vektor

```
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Lokal | good |
| AC Komplexität | Gering | bad |
| PR Privilegien | Gering | warn |
| UI Interaktion | Keine | bad |
| S Scope | Unverändert | good |
| C Vertraulichkeit | Keine | good |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Hoch | bad |

## Exploit-Evidenz

- [EDB-47692 — Ubuntu 19.10 - ubuntu-aufs-modified mmap_region() Breaks Refcounting in overlayfs/shiftfs Error Path](https://www.exploit-db.com/exploits/47692) ✅

## Referenzen

- <https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/eoan/commit/?id=270d16ae48a4dbf1c7e25e94cc3e38b4bea37635>
- <https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/eoan/commit/?id=ef81780548d20a786cc77ed4203fca146fd81ce3>
- <https://usn.ubuntu.com/usn/usn-4208-1>
- <https://usn.ubuntu.com/usn/usn-4209-1>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2019-15794) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_