Detections
Analytics
Amazon Linux 2023 : nginx, nginx-all-modules, nginx-core (ALAS2023-2026-2008)
critical Nessus Plugin ID 331990
Synopsis
The remote Amazon Linux 2023 host is missing a security update.Description
It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2023-2026-2008 advisory.A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and a string expression references the map's regex capture variables before referencing the map output variable.
Alternatively, the same result could be achieved by using a non-cacheable variable in a string expression under certain conditions. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR.
Impact:This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
(CVE-2026-42533)
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module. This vulnerability may exist when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured. With this configuration, an unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream server may be able to cause a use-after-free in the NGINX worker process. This issue may lead to limited modification of memory or a restart of the NGINX worker process.
Impact:This vulnerability may allow remote attackers to have limited control to modify memory contents or restart the NGINX worker process. There is no control plane exposure; this is a data plane issue only.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
(CVE-2026-56434)
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_slice_module module. When the slice directive and unnamed regex captures are configured or when a background cache update happens, unauthenticated attackers can send requests that may cause uninitialized memory access in the NGINX worker process, leading to limited disclosure of memory or a restart.
Impact:This vulnerability may allow remote, unauthenticated attackers to have limited control to disclose memory contents or restart the NGINX worker process. There is no control plane exposure; this is a data plane issue only.Note: The ngx_http_slice_module module is not enabled by default; it's enabled with the
--with-http_slice_module configuration parameter.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
(CVE-2026-60005)
Tenable has extracted the preceding description block directly from the tested product security advisory.
Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.
Solution
Run 'dnf update nginx --releasever 2023.12.20260803' or or 'dnf update --advisory ALAS2023-2026-2008 --releasever 2023.12.20260803' to update your system.See Also
https://alas.aws.amazon.com//AL2023/ALAS2023-2026-2008.html
https://alas.aws.amazon.com/faqs.html
https://explore.alas.aws.amazon.com/CVE-2026-42533.html
Plugin Details
Severity: Critical
ID: 331990
File Name: al2023_ALAS2023-2026-2008.nasl
Version: 1.1
Type: Local
Agent: unix
Published: 8/4/2026
Updated: 8/4/2026
Supported Sensors: Agentless Assessment, Continuous Assessment, Frictionless Assessment Agent, Frictionless Assessment AWS, Nessus Agent, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus
Risk Information
VPR
Risk Factor: High
Score: 7.9
Percentile: 99.35
CVSS v2
Risk Factor: High
Base Score: 8.5
Temporal Score: 6.7
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:N/A:C
CVSS Score Source: CVE-2026-60005
CVSS v3
Risk Factor: High
Base Score: 8.1
Temporal Score: 7.3
Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Temporal Vector: CVSS:3.0/E:P/RL:O/RC:C
CVSS Score Source: CVE-2026-42533
CVSS v4
Risk Factor: Critical
Base Score: 9.2
Threat Score: 8.2
Threat Vector: CVSS:4.0/E:P
Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CVSS Score Source: CVE-2026-42533
Vulnerability Information
CPE: cpe:/o:amazon:linux:2023, p-cpe:/a:amazon:linux:nginx-all-modules, p-cpe:/a:amazon:linux:nginx-core-debuginfo, p-cpe:/a:amazon:linux:nginx-core, p-cpe:/a:amazon:linux:nginx-debuginfo, p-cpe:/a:amazon:linux:nginx-debugsource, p-cpe:/a:amazon:linux:nginx-filesystem, p-cpe:/a:amazon:linux:nginx-mod-devel, p-cpe:/a:amazon:linux:nginx-mod-http-image-filter-debuginfo, p-cpe:/a:amazon:linux:nginx-mod-http-image-filter, p-cpe:/a:amazon:linux:nginx-mod-http-perl-debuginfo, p-cpe:/a:amazon:linux:nginx-mod-http-perl, p-cpe:/a:amazon:linux:nginx-mod-http-xslt-filter-debuginfo, p-cpe:/a:amazon:linux:nginx-mod-http-xslt-filter, p-cpe:/a:amazon:linux:nginx-mod-mail-debuginfo, p-cpe:/a:amazon:linux:nginx-mod-mail, p-cpe:/a:amazon:linux:nginx-mod-stream-debuginfo, p-cpe:/a:amazon:linux:nginx-mod-stream, p-cpe:/a:amazon:linux:nginx
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: 8/4/2026
Vulnerability Publication Date: 7/15/2026
Reference Information
CVE: CVE-2026-42533, CVE-2026-56434, CVE-2026-60005
IAVA: 2026-A-0754