Detections
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Amazon Linux 2 : mod_http2 (ALAS-2021-1678)

high Nessus Plugin ID 151277

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Synopsis

The remote Amazon Linux 2 host is missing a security update.

Description

The version of mod_http2 installed on the remote host is prior to 1.15.19-1. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2021-1678 advisory.

 - Apache HTTP Server protocol handler for the HTTP/2 protocol checks received request headers against the size limitations as configured for the server and used for the HTTP/1 protocol as well. On violation of these restrictions and HTTP response is sent to the client with a status code indicating why the request was rejected. This rejection response was not fully initialised in the HTTP/2 protocol handler if the offending header was the very first one received or appeared in a a footer. This led to a NULL pointer dereference on initialised memory, crashing reliably the child process. Since such a triggering HTTP/2 request is easy to craft and submit, this can be exploited to DoS the server. This issue affected mod_http2 1.15.17 and Apache HTTP Server version 2.4.47 only. Apache HTTP Server 2.4.47 was never released. (CVE-2021-31618)

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

Solution

Run 'yum update mod_http2' to update your system.

See Also

https://alas.aws.amazon.com/AL2/ALAS-2021-1678.html

https://access.redhat.com/security/cve/CVE-2021-31618

Plugin Details

Severity: High

ID: 151277

File Name: al2_ALAS-2021-1678.nasl

Version: 1.3

Type: local

Agent: unix

Published: 7/1/2021

Updated: 9/24/2021

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

Risk Information

VPR

Risk Factor: Low

Score: 3.6

CVSS v2

Risk Factor: Medium

Base Score: 5

Temporal Score: 3.7

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

CVSS Score Source: CVE-2021-31618

CVSS v3

Risk Factor: High

Base Score: 7.5

Temporal Score: 6.5

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

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

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:mod_http2, p-cpe:/a:amazon:linux:mod_http2-debuginfo, cpe:/o:amazon:linux:2

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

Exploit Ease: No known exploits are available

Patch Publication Date: 7/1/2021

Vulnerability Publication Date: 6/1/2021

Reference Information

CVE: CVE-2021-31618

ALAS: 2021-1678

IAVA: 2021-A-0259-S