CVE-2019-15791

Reference count underflow in shiftfs

Severity Score

7.8

*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

*Multiple Sources

Exploited in Wild

*KEV

Decision

*SSVC

Descriptions

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.

En shiftfs, un parche no upstream para el Kernel de Linux incluido en las series kernel de Ubuntu versiones 5.0 y 5.3, shiftfs_btrfs_ioctl_fd_replace() instala un fd que hace referencia a un archivo del sistema de archivos inferior sin tomar una referencia adicional a ese archivo. Después de que el btrfs ioctl completa este fd se cierra, lo que entonces pone una referencia a ese archivo, lo que lleva a un subflujo de recuento.

*Credits: Jann Horn of Google Project Zero

CVSS Scores

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

High

Attack Vector

Local

Attack Complexity

Low

Authentication

None

Confidentiality

Partial

Integrity

Partial

Availability

Partial

* Common Vulnerability Scoring System

SSVC

Decision:-

Exploitation

Automatable

Tech. Impact

* Organization's Worst-case Scenario

Timeline

2019-08-29 CVE Reserved
2019-11-13 CVE Published
2019-11-20 First Exploit
2023-03-08 EPSS Updated
2024-09-17 CVE Updated
---------- Exploited in Wild
---------- KEV Due Date

CWE

CWE-191: Integer Underflow (Wrap or Wraparound)
CWE-672: Operation on a Resource after Expiration or Release

CAPEC

References (4)

URL	Tag	Source
https://usn.ubuntu.com/usn/usn-4183-1	Third Party Advisory
https://usn.ubuntu.com/usn/usn-4184-1	Third Party Advisory

URL	Date	SRC
https://www.exploit-db.com/exploits/47693	2019-11-20

URL	Date	SRC
https://git.launchpad.net/~ubuntu-kernel/ubuntu/+source/linux/+git/eoan/commit/?id=601a64857b3d7040ca15c39c929e6b9db3373ec1	2020-05-01

URL	Date	SRC

Affected Vendors, Products, and Versions

Vendor		Product				Version		Other		Status
Vendor	Product	Version	Other	Status	<-- -->	Vendor	Product	Version	Other	Status
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				5.0 Search vendor "Linux" for product "Linux Kernel" and version "5.0"		-		Affected
Linux Search vendor "Linux"		Linux Kernel Search vendor "Linux" for product "Linux Kernel"				5.3 Search vendor "Linux" for product "Linux Kernel" and version "5.3"		-		Affected
Canonical Search vendor "Canonical"		Ubuntu Linux Search vendor "Canonical" for product "Ubuntu Linux"				18.04 Search vendor "Canonical" for product "Ubuntu Linux" and version "18.04"		lts		Affected
Canonical Search vendor "Canonical"		Ubuntu Linux Search vendor "Canonical" for product "Ubuntu Linux"				19.04 Search vendor "Canonical" for product "Ubuntu Linux" and version "19.04"		-		Affected