Amazon Linux AMI : kernel (ALAS-2019-1205) (MDSUM/RIDL) (MFBDS/RIDL/ZombieLoad) (MLPDS/RIDL) (MSBDS/Fallout)

medium Nessus Plugin ID 125092


The remote Amazon Linux AMI host is missing a security update.


- Microarchitectural Store Buffer Data Sampling (MSBDS) (CVE-2018-12126)

- Microarchitectural Fill Buffer Data Sampling (MFBDS) (CVE-2018-12130)

- Microarchitectural Load Port Data Sampling (MLPDS) (CVE-2018-12127)

- Microarchitectural Data Sampling Uncacheable Memory (MDSUM) (CVE-2019-11091)

MSBDS leaks Store Buffer Entries which can be speculatively forwarded to a dependent load (store-to-load forwarding) as an optimization. The forward can also happen to a faulting or assisting load operation for a different memory address, which can cause an issue under certain conditions. Store buffers are partitioned between Hyper-Threads so cross thread forwarding is not possible. But if a thread enters or exits a sleep state the store buffer is repartitioned which can expose data from one thread to the other.

MFBDS leaks Fill Buffer Entries. Fill buffers are used internally to manage L1 miss situations and to hold data which is returned or sent in response to a memory or I/O operation. Fill buffers can forward data to a load operation and also write data to the cache. When the fill buffer is deallocated it can retain the stale data of the preceding operations which can then be forwarded to a faulting or assisting load operation, which can cause an issue under certain conditions. Fill buffers are shared between Hyper-Threads so cross thread leakage is possible.

MLDPS leaks Load Port Data. Load ports are used to perform load operations from memory or I/O. The received data is then forwarded to the register file or a subsequent operation. In some implementations the Load Port can contain stale data from a previous operation which can be forwarded to faulting or assisting loads under certain conditions, which again can cause an issue eventually. Load ports are shared between Hyper-Threads so cross thread leakage is possible.


Run 'yum update kernel' and reboot your instance to update your system.

See Also

Plugin Details

Severity: Medium

ID: 125092

File Name: ala_ALAS-2019-1205.nasl

Version: 1.6

Type: local

Agent: unix

Published: 5/15/2019

Updated: 5/28/2024

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

Risk Information


Risk Factor: Medium

Score: 6.0


Risk Factor: Medium

Base Score: 4.7

Temporal Score: 3.7

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

CVSS Score Source: CVE-2019-11091


Risk Factor: Medium

Base Score: 5.6

Temporal Score: 5.1

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

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

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:perf, p-cpe:/a:amazon:linux:perf-debuginfo, p-cpe:/a:amazon:linux:kernel-tools-debuginfo, p-cpe:/a:amazon:linux:kernel-tools-devel, p-cpe:/a:amazon:linux:kernel-tools, p-cpe:/a:amazon:linux:kernel-devel, p-cpe:/a:amazon:linux:kernel, p-cpe:/a:amazon:linux:kernel-debuginfo, p-cpe:/a:amazon:linux:kernel-headers, p-cpe:/a:amazon:linux:kernel-debuginfo-common-i686, p-cpe:/a:amazon:linux:kernel-debuginfo-common-x86_64, cpe:/o:amazon:linux

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Available: true

Exploit Ease: Exploits are available

Patch Publication Date: 5/7/2019

Vulnerability Publication Date: 5/30/2019

Reference Information

CVE: CVE-2018-12126, CVE-2018-12127, CVE-2018-12130, CVE-2019-11091

ALAS: 2019-1205