Ubuntu 18.04 LTS / 20.04 LTS : Linux kernel vulnerabilities (USN-4750-1)

high Nessus Plugin ID 148009

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Synopsis

The remote Ubuntu host is missing one or more security updates.

Description

The remote Ubuntu 18.04 LTS / 20.04 LTS host has packages installed that are affected by multiple vulnerabilities as referenced in the USN-4750-1 advisory.

 - An issue was discovered in drivers/accessibility/speakup/spk_ttyio.c in the Linux kernel through 5.9.9.
 Local attackers on systems with the speakup driver could cause a local denial of service attack, aka CID-d41227544427. This occurs because of an invalid free when the line discipline is used more than once.
 (CVE-2020-28941)

 - An issue was discovered in Xen through 4.14.x. Some OSes (such as Linux, FreeBSD, and NetBSD) are processing watch events using a single thread. If the events are received faster than the thread is able to handle, they will get queued. As the queue is unbounded, a guest may be able to trigger an OOM in the backend. All systems with a FreeBSD, Linux, or NetBSD (any version) dom0 are vulnerable. (CVE-2020-29568)

 - An issue was discovered in the Linux kernel through 5.10.1, as used with Xen through 4.14.x. The Linux kernel PV block backend expects the kernel thread handler to reset ring->xenblkd to NULL when stopped.
 However, the handler may not have time to run if the frontend quickly toggles between the states connect and disconnect. As a consequence, the block backend may re-use a pointer after it was freed. A misbehaving guest can trigger a dom0 crash by continuously connecting / disconnecting a block frontend. Privilege escalation and information leaks cannot be ruled out. This only affects systems with a Linux blkback.
 (CVE-2020-29569)

 - A locking inconsistency issue was discovered in the tty subsystem of the Linux kernel through 5.9.13.
 drivers/tty/tty_io.c and drivers/tty/tty_jobctrl.c may allow a read-after-free attack against TIOCGSID, aka CID-c8bcd9c5be24. (CVE-2020-29660)

 - A locking issue was discovered in the tty subsystem of the Linux kernel through 5.9.13.
 drivers/tty/tty_jobctrl.c allows a use-after-free attack against TIOCSPGRP, aka CID-54ffccbf053b.
 (CVE-2020-29661)

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Update the affected packages.

See Also

https://ubuntu.com/security/notices/USN-4750-1

Plugin Details

Severity: High

ID: 148009

File Name: ubuntu_USN-4750-1.nasl

Version: 1.5

Type: local

Agent: unix

Published: 3/23/2021

Updated: 1/17/2023

Supported Sensors: Agentless Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Frictionless Assessment Azure, Nessus Agent

Risk Information

VPR

Risk Factor: High

Score: 7.3

CVSS v2

Risk Factor: High

Base Score: 7.2

Temporal Score: 5.6

Vector: CVSS2#AV:L/AC:L/Au:N/C:C/I:C/A:C

Temporal Vector: CVSS2#E:POC/RL:OF/RC:C

CVSS Score Source: CVE-2020-29661

CVSS v3

Risk Factor: High

Base Score: 8.8

Temporal Score: 7.9

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C

CVSS Score Source: CVE-2020-29569

Vulnerability Information

CPE: p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1037-gcp, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1038-aws, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1038-oracle, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1040-azure, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-66-generic, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-66-generic-lpae, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-66-lowlatency, p-cpe:/a:canonical:ubuntu_linux:linux-image-aws, p-cpe:/a:canonical:ubuntu_linux:linux-image-aws-edge, p-cpe:/a:canonical:ubuntu_linux:linux-image-azure, p-cpe:/a:canonical:ubuntu_linux:linux-image-azure-edge, p-cpe:/a:canonical:ubuntu_linux:linux-image-gcp, p-cpe:/a:canonical:ubuntu_linux:linux-image-gcp-edge, p-cpe:/a:canonical:ubuntu_linux:linux-image-generic, p-cpe:/a:canonical:ubuntu_linux:linux-image-generic-hwe-18.04, p-cpe:/a:canonical:ubuntu_linux:linux-image-generic-hwe-18.04-edge, p-cpe:/a:canonical:ubuntu_linux:linux-image-generic-lpae, p-cpe:/a:canonical:ubuntu_linux:linux-image-generic-lpae-hwe-18.04, p-cpe:/a:canonical:ubuntu_linux:linux-image-generic-lpae-hwe-18.04-edge, p-cpe:/a:canonical:ubuntu_linux:linux-image-gke-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-image-gkeop, p-cpe:/a:canonical:ubuntu_linux:linux-image-gkeop-5.4, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1010-gkeop, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1029-raspi, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1033-kvm, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1036-gke, p-cpe:/a:canonical:ubuntu_linux:linux-image-kvm, p-cpe:/a:canonical:ubuntu_linux:linux-image-lowlatency, p-cpe:/a:canonical:ubuntu_linux:linux-image-lowlatency-hwe-18.04, p-cpe:/a:canonical:ubuntu_linux:linux-image-lowlatency-hwe-18.04-edge, p-cpe:/a:canonical:ubuntu_linux:linux-image-oem, p-cpe:/a:canonical:ubuntu_linux:linux-image-oem-osp1, p-cpe:/a:canonical:ubuntu_linux:linux-image-oracle, p-cpe:/a:canonical:ubuntu_linux:linux-image-oracle-edge, p-cpe:/a:canonical:ubuntu_linux:linux-image-raspi, p-cpe:/a:canonical:ubuntu_linux:linux-image-raspi-hwe-18.04, p-cpe:/a:canonical:ubuntu_linux:linux-image-raspi-hwe-18.04-edge, p-cpe:/a:canonical:ubuntu_linux:linux-image-raspi2, p-cpe:/a:canonical:ubuntu_linux:linux-image-raspi2-hwe-18.04, p-cpe:/a:canonical:ubuntu_linux:linux-image-raspi2-hwe-18.04-edge, p-cpe:/a:canonical:ubuntu_linux:linux-image-snapdragon-hwe-18.04, p-cpe:/a:canonical:ubuntu_linux:linux-image-snapdragon-hwe-18.04-edge, p-cpe:/a:canonical:ubuntu_linux:linux-image-virtual, p-cpe:/a:canonical:ubuntu_linux:linux-image-virtual-hwe-18.04, p-cpe:/a:canonical:ubuntu_linux:linux-image-virtual-hwe-18.04-edge

Required KB Items: Host/cpu, Host/Ubuntu, Host/Ubuntu/release, Host/Debian/dpkg-l

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 2/25/2021

Vulnerability Publication Date: 11/19/2020

Reference Information

CVE: CVE-2020-25669, CVE-2020-27815, CVE-2020-27830, CVE-2020-28588, CVE-2020-28941, CVE-2020-29568, CVE-2020-29569, CVE-2020-29660, CVE-2020-29661, CVE-2021-20177

USN: 4750-1