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Ubuntu 16.04 LTS / 18.04 LTS : Linux kernel vulnerabilities (USN-4749-1)

high Nessus Plugin ID 147983

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Synopsis

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

Description

The remote Ubuntu 16.04 LTS / 18.04 LTS host has a package installed that is affected by multiple vulnerabilities as referenced in the USN-4749-1 advisory.

 - A vulnerability was found in the Linux Kernel where the function sunkbd_reinit having been scheduled by sunkbd_interrupt before sunkbd being freed. Though the dangling pointer is set to NULL in sunkbd_disconnect, there is still an alias in sunkbd_reinit causing Use After Free. (CVE-2020-25669)

 - A flaw was found in the JFS filesystem code in the Linux Kernel which allows a local attacker with the ability to set extended attributes to panic the system, causing memory corruption or escalating privileges. The highest threat from this vulnerability is to confidentiality, integrity, as well as system availability. (CVE-2020-27815)

 - A vulnerability was found in Linux Kernel where in the spk_ttyio_receive_buf2() function, it would dereference spk_ttyio_synth without checking whether it is NULL or not, and may lead to a NULL-ptr deref crash. (CVE-2020-27830)

 - 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 the Linux kernel before 5.7.3, related to mm/gup.c and mm/huge_memory.c. The get_user_pages (aka gup) implementation, when used for a copy-on-write page, does not properly consider the semantics of read operations and therefore can grant unintended write access, aka CID-17839856fd58.
 (CVE-2020-29374)

 - 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 these issues but has instead relied only on the application's self-reported version number.

Solution

Update the affected kernel package.

See Also

https://ubuntu.com/security/notices/USN-4749-1

Plugin Details

Severity: High

ID: 147983

File Name: ubuntu_USN-4749-1.nasl

Version: 1.7

Type: local

Agent: unix

Published: 3/23/2021

Updated: 1/9/2024

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

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

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: cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15.0-1012-dell300x, p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15.0-1065-oracle, p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15.0-1079-gke, p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15.0-1079-raspi2, p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15.0-1085-kvm, p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15.0-1093-gcp, p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15.0-1094-aws, p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15.0-1096-snapdragon, p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15.0-1108-azure, p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15.0-136-generic, p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15.0-136-generic-lpae, p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15.0-136-lowlatency

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-2020-28941, CVE-2020-29374, CVE-2020-29568, CVE-2020-29569, CVE-2020-29660, CVE-2020-29661

USN: 4749-1