CVE-2019-15791 Reference count underflow in shiftfs

2019-11-1200:00:00

CWE-672

canonical

www.cve.org

CVSS3

7.1

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

HIGH

Availability Impact

HIGH

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

AI Score

7.7

Confidence

High

EPSS

Percentile

12.6%

JSON

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.

CNA Affected

[
  {
    "product": "Shiftfs in the Linux kernel",
    "vendor": "Ubuntu",
    "versions": [
      {
        "changes": [
          {
            "at": "5.3.0-22.24",
            "status": "unaffected"
          }
        ],
        "lessThan": "5.3 kernel*",
        "status": "affected",
        "version": "5.3.0-11.12",
        "versionType": "custom"
      },
      {
        "lessThan": "5.0.0-35.38",
        "status": "affected",
        "version": "5.0 kernel",
        "versionType": "custom"
      }
    ]
  }
]