Heap-based buffer overflow in NGINX Plus and NGINX Open Source - CVE-2026-42945

Vulnerability identifier: #VU131377

CSH Severity: Critical

CVSS v4: 9.2 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-42945

CWE-ID: CWE-122

Exploitation vector: Remote access

Exploit availability: The vulnerability is being exploited in the wild

The vulnerability allows a remote attacker to cause a denial of service or execute arbitrary code.

The vulnerability exists due to heap-based buffer overflow in ngx_http_rewrite_module when processing crafted HTTP requests that reach configurations where a rewrite directive is followed by a rewrite, if, or set directive and unnamed PCRE captures are used with a replacement string containing a question mark. A remote attacker can send crafted HTTP requests to cause a denial of service or execute arbitrary code.

Code execution is possible on systems with address space layout randomization disabled. There is no control plane exposure; this is a data plane issue only.

NGINX Plus
NGINX Open Source
Gentoo Linux
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15 SP6
Debian Linux
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15
SUSE Linux Enterprise High Performance Computing LTSS 15
SUSE Linux Enterprise High Performance Computing ESPOS 15
SUSE Linux Enterprise High Performance Computing 15
SUSE Linux Enterprise Server for SAP Applications 15
SUSE Linux Enterprise Real Time 15
Anolis OS
Red Hat Enterprise Linux for IBM z Systems
Red Hat Enterprise Linux for Power, little endian
Red Hat Enterprise Linux for ARM 64
Red Hat Enterprise Linux for x86_64
Red Hat Enterprise Linux Server - AUS
Red Hat Enterprise Linux for x86_64 - Extended Update Support
Red Hat Enterprise Linux for IBM z Systems - Extended Update Support
Red Hat Enterprise Linux for Power, little endian - Extended Update Support
Red Hat Enterprise Linux for ARM 64 - Extended Update Support
Red Hat CodeReady Linux Builder for ARM 64 - Extended Update Support
Red Hat CodeReady Linux Builder for x86_64 - Extended Update Support
Red Hat CodeReady Linux Builder for IBM z Systems - Extended Update Support
Red Hat CodeReady Linux Builder for Power, little endian - Extended Update Support
Ubuntu
Server Applications Module
openSUSE Leap
openEuler
Fedora
Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions
nginx-mod-js-challenge
nginx-mod-vts
nginx-mod-fancyindex
nginx-mod-headers-more
nginx-mod-brotli
nginx-mod-modsecurity
nginx (Ubuntu package)
nginx-mod-naxsi
nginx
nginx-filesystem
nginx-all-modules
nginx-mod-stream
nginx-mod-mail
nginx-mod-http-xslt-filter
nginx-mod-http-perl
nginx-mod-http-image-filter
nginx-mod-devel
nginx (Red Hat package)
nginx-debugsource
nginx-debuginfo
nginx-help
nginx-source
nginx (Debian package)
compat-nginx-filesystem
compat-nginx-mod-stream
compat-nginx-mod-mail
compat-nginx-all-modules
compat-nginx-help
compat-nginx-mod-http-perl
compat-nginx-mod-http-image-filter
compat-nginx-debugsource
compat-nginx-debuginfo
compat-nginx
compat-nginx-mod-http-xslt-filter
nginx-core
nginx-doc
www-servers/nginx

Install security update from vendor's website.

NGINX Plus - addressed in versions R32 P6, R36 P4
NGINX Open Source - update to 1.30.1
nginx-mod-js-challenge - update to 0^20230517.gitda6852d-7.fc44
nginx-mod-vts - addressed in versions 0.2.4-9.fc42, 0.2.4-9.fc43, 0.2.4-9.fc44
nginx-mod-fancyindex - addressed in versions 0.6.0-4.fc42, 0.6.0-4.fc43, 0.6.0-4.fc44
nginx-mod-headers-more - addressed in versions 0.39-9.fc42, 0.39-9.fc43, 0.39-9.fc44
nginx-mod-brotli - addressed in versions 1.0.0~rc-9.fc42, 1.0.0~rc-9.fc43, 1.0.0~rc-9.fc44
nginx-mod-modsecurity - addressed in versions 1.0.4-10.fc42, 1.0.4-10.fc43, 1.0.4-10.fc44
nginx (Ubuntu package) - addressed in versions 1.4.6-1ubuntu3.9+esm6, 1.10.3-0ubuntu0.16.04.5+esm7, 1.14.0-0ubuntu1.11+esm2, 1.18.0-0ubuntu1.7+esm1, 1.18.0-6ubuntu14.11, 1.24.0-2ubuntu7.8, 1.28.0-6ubuntu1.3, 1.28.3-2ubuntu1.1
nginx-mod-naxsi - addressed in versions 1.6-17.fc42, 1.6-17.fc43, 1.6-17.fc44
nginx - addressed in versions 1.20.1-1.0.7, 1.22.1-1.0.3, 1.26.2-9
nginx-filesystem - addressed in versions 1.20.1-1.0.7, 1.22.1-1.0.3, 1.26.2-9
nginx-all-modules - addressed in versions 1.20.1-1.0.7, 1.22.1-1.0.3, 1.26.2-9
nginx-mod-stream - addressed in versions 1.20.1-1.0.7, 1.22.1-1.0.3, 1.26.2-9
nginx-mod-mail - addressed in versions 1.20.1-1.0.7, 1.22.1-1.0.3, 1.26.2-9
nginx-mod-http-xslt-filter - addressed in versions 1.20.1-1.0.7, 1.22.1-1.0.3, 1.26.2-9
nginx-mod-http-perl - addressed in versions 1.20.1-1.0.7, 1.22.1-1.0.3, 1.26.2-9
nginx-mod-http-image-filter - addressed in versions 1.20.1-1.0.7, 1.22.1-1.0.3, 1.26.2-9
nginx-mod-devel - addressed in versions 1.20.1-1.0.7, 1.22.1-1.0.3, 1.26.2-9
nginx (Red Hat package) - addressed in versions 1.20.1-10.el9_0.4, 1.20.1-14.el9_2.6, 1.20.1-22.el9_6.6, 1.20.1-24.el9_7.3, 1.20.1-28.el9_8.2, 1.26.3-1.el10_0.9
nginx-mod-http-xslt-filter - addressed in versions 1.21.5-11, 1.21.5-13, 1.24.0-9, 1.24.0-10
nginx-debugsource - addressed in versions 1.21.5-11, 1.21.5-13, 1.24.0-9, 1.24.0-10
nginx-mod-http-perl - addressed in versions 1.21.5-11, 1.21.5-13, 1.24.0-9, 1.24.0-10
nginx-mod-devel - addressed in versions 1.21.5-11, 1.21.5-13, 1.24.0-9, 1.24.0-10
nginx-mod-http-image-filter - addressed in versions 1.21.5-11, 1.21.5-13, 1.24.0-9, 1.24.0-10
nginx-filesystem - addressed in versions 1.21.5-11, 1.21.5-13, 1.24.0-9, 1.24.0-10
nginx-all-modules - addressed in versions 1.21.5-11, 1.21.5-13, 1.24.0-9, 1.24.0-10
nginx-mod-stream - addressed in versions 1.21.5-11, 1.21.5-13, 1.24.0-9, 1.24.0-10
nginx-mod-mail - addressed in versions 1.21.5-11, 1.21.5-13, 1.24.0-9, 1.24.0-10
nginx-debuginfo - addressed in versions 1.21.5-11, 1.21.5-13, 1.24.0-9, 1.24.0-10
nginx - addressed in versions 1.21.5-11, 1.21.5-13, 1.24.0-9, 1.24.0-10
nginx-help - addressed in versions 1.21.5-13, 1.24.0-9, 1.24.0-10
nginx-source - addressed in versions 1.21.5-150400.3.20.1, 1.21.5-150600.10.18.1
nginx - addressed in versions 1.21.5-150400.3.20.1, 1.21.5-150600.10.18.1
nginx-debuginfo - addressed in versions 1.21.5-150400.3.20.1, 1.21.5-150600.10.18.1
nginx-debugsource - addressed in versions 1.21.5-150400.3.20.1, 1.21.5-150600.10.18.1
nginx (Debian package) - addressed in versions 1.22.1-9+deb12u7, 1.26.3-3+deb13u5
compat-nginx-filesystem - update to 1.24.0-10
compat-nginx-mod-stream - update to 1.24.0-10
compat-nginx-mod-mail - update to 1.24.0-10
compat-nginx-all-modules - update to 1.24.0-10
compat-nginx-help - update to 1.24.0-10
compat-nginx-mod-http-perl - update to 1.24.0-10
compat-nginx-mod-http-image-filter - update to 1.24.0-10
compat-nginx-debugsource - update to 1.24.0-10
compat-nginx-debuginfo - update to 1.24.0-10
compat-nginx - update to 1.24.0-10
compat-nginx-mod-http-xslt-filter - update to 1.24.0-10
nginx-core - update to 1.26.2-9
nginx-doc - update to 1.26.2-9
nginx - addressed in versions 1.30.1-1.fc42, 1.30.1-1.fc43, 1.30.1-1.fc44
www-servers/nginx - update to 1.31.3-r1

• Exploit #12747 - CVE-2026-42945-POC (exploit for CVE-2026-42945) (May 22, 2026)
• Exploit #12732 - cve-2026-42945-nginx32-lab (CVE-2026-42945 nginx 32-bit exploit lab ASLR enabled) (May 22, 2026)

• https://my.f5.com/manage/s/article/K000161019

• Multiple vulnerabilities in NGINX Open Source and NGINX Plus
• Fedora 44 update for nginx, nginx-mod-brotli, nginx-mod-fancyindex, nginx-mod-headers-more, nginx-mod-js-challenge, nginx-mod-modsecurity, nginx-mod-naxsi, nginx-mod-vts
• Fedora 43 update for nginx, nginx-mod-brotli, nginx-mod-fancyindex, nginx-mod-headers-more, nginx-mod-modsecurity, nginx-mod-naxsi, nginx-mod-vts
• Fedora 42 update for nginx, nginx-mod-brotli, nginx-mod-fancyindex, nginx-mod-headers-more, nginx-mod-modsecurity, nginx-mod-naxsi, nginx-mod-vts
• Red Hat Enterprise Linux 9 update for nginx
• Red Hat Enterprise Linux 9 update for the nginx:1.24 module
• Red Hat Enterprise Linux 9 update for the nginx:1.26 module
• Anolis OS update for nginx:1.22 module
• Anolis OS update for nginx:1.20 module
• Anolis OS update for nginx
• Red Hat Enterprise Linux 10 update for nginx
• Red Hat Enterprise Linux 9 update for nginx
• Red Hat Enterprise Linux 9 update for the nginx:1.24 module
• Red Hat Enterprise Linux 9 update for nginx
• Red Hat Enterprise Linux 9 update for nginx
• Ubuntu update for nginx
• Debian update for nginx
• Red Hat Enterprise Linux 9 update for the nginx:1.24 module
• Red Hat Enterprise Linux 9 update for the nginx:1.26 module
• Red Hat Enterprise Linux 9 update for nginx
• openEuler 24.03 LTS SP3 update for nginx
• openEuler 24.03 LTS update for nginx
• openEuler 22.03 LTS SP4 update for nginx
• openEuler 20.03 LTS SP4 update for nginx
• SUSE update for nginx
• openEuler 24.03 LTS SP1 update for nginx
• Ubuntu update for nginx
• SUSE update for nginx
• Gentoo update for nginx