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Ubuntu 16.04 LTS / 18.04 LTS : Linux kernel vulnerabilities (USN-4318-1)

high Nessus Plugin ID 135269

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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-4318-1 advisory.

 - fs/namei.c in the Linux kernel before 5.5 has a may_create_in_sticky use-after-free, which allows local users to cause a denial of service (OOPS) or possibly obtain sensitive information from kernel memory, aka CID-d0cb50185ae9. One attack vector may be an open system call for a UNIX domain socket, if the socket is being moved to a new parent directory and its old parent directory is being removed. (CVE-2020-8428)

 - KVM in the Linux kernel on Power8 processors has a conflicting use of HSTATE_HOST_R1 to store r1 state in kvmppc_hv_entry plus in kvmppc_{save,restore}_tm, leading to a stack corruption. Because of this, an attacker with the ability run code in kernel space of a guest VM can cause the host kernel to panic. There were two commits that, according to the reporter, introduced the vulnerability: f024ee098476 (KVM: PPC:
 Book3S HV: Pull out TM state save/restore into separate procedures) 87a11bb6a7f7 (KVM: PPC: Book3S HV:
 Work around XER[SO] bug in fake suspend mode) The former landed in 4.8, the latter in 4.17. This was fixed without realizing the impact in 4.18 with the following three commits, though it's believed the first is the only strictly necessary commit: 6f597c6b63b6 (KVM: PPC: Book3S PR: Add guest MSR parameter for kvmppc_save_tm()/kvmppc_restore_tm()) 7b0e827c6970 (KVM: PPC: Book3S HV: Factor fake-suspend handling out of kvmppc_save/restore_tm) 009c872a8bc4 (KVM: PPC: Book3S PR: Move kvmppc_save_tm/kvmppc_restore_tm to separate file) (CVE-2020-8834)

 - ext4_protect_reserved_inode in fs/ext4/block_validity.c in the Linux kernel through 5.5.3 allows attackers to cause a denial of service (soft lockup) via a crafted journal size. (CVE-2020-8992)

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-4318-1

Plugin Details

Severity: High

ID: 135269

File Name: ubuntu_USN-4318-1.nasl

Version: 1.6

Type: local

Agent: unix

Published: 4/7/2020

Updated: 1/9/2024

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

Risk Information

VPR

Risk Factor: Medium

Score: 6.0

CVSS v2

Risk Factor: Low

Base Score: 3.6

Temporal Score: 2.8

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

CVSS Score Source: CVE-2020-8428

CVSS v3

Risk Factor: High

Base Score: 7.1

Temporal Score: 6.4

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

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

Vulnerability Information

CPE: p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15.0-96-generic, p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15.0-96-generic-lpae, p-cpe:/a:canonical:ubuntu_linux:linux-image-4.15.0-96-lowlatency, cpe:/o:canonical:ubuntu_linux:16.04:-:lts, cpe:/o:canonical:ubuntu_linux:18.04:-:lts

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

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 4/6/2020

Vulnerability Publication Date: 1/29/2020

Reference Information

CVE: CVE-2020-8428, CVE-2020-8834, CVE-2020-8992

USN: 4318-1