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Ubuntu 18.04 LTS / 20.04 LTS : Linux kernel vulnerabilities (USN-4909-1)

high Nessus Plugin ID 148497

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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 a package installed that is affected by multiple vulnerabilities as referenced in the USN-4909-1 advisory.

 - There is a vulnerability in the linux kernel versions higher than 5.2 (if kernel compiled with config params CONFIG_BPF_SYSCALL=y , CONFIG_BPF=y , CONFIG_CGROUPS=y , CONFIG_CGROUP_BPF=y , CONFIG_HARDENED_USERCOPY not set, and BPF hook to getsockopt is registered). As result of BPF execution, the local user can trigger bug in __cgroup_bpf_run_filter_getsockopt() function that can lead to heap overflow (because of non-hardened usercopy). The impact of attack could be deny of service or possibly privileges escalation. (CVE-2021-20194)

 - An issue was discovered in the Linux kernel 3.11 through 5.10.16, as used by Xen. To service requests to the PV backend, the driver maps grant references provided by the frontend. In this process, errors may be encountered. In one case, an error encountered earlier might be discarded by later processing, resulting in the caller assuming successful mapping, and hence subsequent operations trying to access space that wasn't mapped. In another case, internal state would be insufficiently updated, preventing safe recovery from the error. This affects drivers/block/xen-blkback/blkback.c. (CVE-2021-26930)

 - An issue was discovered in the Linux kernel 2.6.39 through 5.10.16, as used in Xen. Block, net, and SCSI backends consider certain errors a plain bug, deliberately causing a kernel crash. For errors potentially being at least under the influence of guests (such as out of memory conditions), it isn't correct to assume a plain bug. Memory allocations potentially causing such crashes occur only when Linux is running in PV mode, though. This affects drivers/block/xen-blkback/blkback.c and drivers/xen/xen-scsiback.c.
 (CVE-2021-26931)

 - nbd_add_socket in drivers/block/nbd.c in the Linux kernel through 5.10.12 has an ndb_queue_rq use-after- free that could be triggered by local attackers (with access to the nbd device) via an I/O request at a certain point during device setup, aka CID-b98e762e3d71. (CVE-2021-3348)

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-4909-1

Plugin Details

Severity: High

ID: 148497

File Name: ubuntu_USN-4909-1.nasl

Version: 1.5

Type: local

Agent: unix

Published: 4/14/2021

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: Medium

Score: 6.7

CVSS v2

Risk Factor: Medium

Base Score: 4.6

Temporal Score: 3.4

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

CVSS Score Source: CVE-2021-26930

CVSS v3

Risk Factor: High

Base Score: 7.8

Temporal Score: 6.8

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

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

Vulnerability Information

CPE: cpe:/o:canonical:ubuntu_linux:18.04:-:lts, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1013-gkeop, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1033-raspi, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1037-kvm, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1040-gke, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1041-gcp, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1042-oracle, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1043-aws, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-1044-azure, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-71-generic, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-71-generic-lpae, p-cpe:/a:canonical:ubuntu_linux:linux-image-5.4.0-71-lowlatency

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

Exploit Ease: No known exploits are available

Patch Publication Date: 4/13/2021

Vulnerability Publication Date: 2/1/2021

Reference Information

CVE: CVE-2021-20194, CVE-2021-26930, CVE-2021-26931, CVE-2021-3348

USN: 4909-1