CVE-2019-15794

medium
New! CVE Severity Now Using CVSS v3

The calculated severity for CVEs has been updated to use CVSS v3 by default. CVEs that do not have a CVSS v3 score will fall back CVSS v2 for calculating severity. Severity display preferences can be toggled in the settings dropdown.

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.

References

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

Details

Source: MITRE

Published: 2020-04-24

Updated: 2020-05-26

Type: CWE-672

Risk Information

CVSS v2

Base Score: 7.2

Vector: AV:L/AC:L/Au:N/C:C/I:C/A:C

Impact Score: 10

Exploitability Score: 3.9

Severity: HIGH

CVSS v3

Base Score: 6.7

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

Impact Score: 5.9

Exploitability Score: 0.8

Severity: MEDIUM

Tenable Plugins

View all (2 total)

IDNameProductFamilySeverity
131563Ubuntu 18.04 LTS / 19.04 : linux, linux-aws, linux-aws-5.0, linux-gcp, linux-gke-5.0, linux-hwe, (USN-4209-1)NessusUbuntu Local Security Checks
critical
131562Ubuntu 18.04 LTS / 19.10 : linux, linux-aws, linux-gcp, linux-gcp-5.3, linux-kvm, linux-oracle (USN-4208-1)NessusUbuntu Local Security Checks
critical