Use-after-free in NGINX Plus and NGINX Open Source - CVE-2026-40701

Vulnerability identifier: #VU131379

CSH Severity: Medium

CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-40701

CWE-ID: CWE-416

Exploitation vector: Remote access

Exploit availability: No public exploit available

The vulnerability allows a remote attacker to cause a denial of service or modify data in a limited manner.

The vulnerability exists due to use-after-free in ngx_http_ssl_module when handling requests with client certificate verification and OCSP checking enabled. A remote attacker can send requests that trigger the flaw to cause a denial of service or modify data in a limited manner.

This issue affects the data plane only. Exploitation requires the ssl_verify_client directive to be set to "on" or "optional," and the ssl_ocsp directive to be set to "on" or configured with the leaf parameter and a resolver.

NGINX Plus
NGINX Open Source
Gentoo Linux
Debian Linux
SUSE Linux Enterprise Server 15 SP4
SUSE Linux Enterprise Server 15 SP5
SUSE Linux Enterprise Server 15 SP6
SUSE Linux Enterprise Server for SAP Applications 15
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 Real Time 15
Ubuntu
Server Applications Module
openSUSE Leap
openEuler
Fedora
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-mod-devel
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-debugsource
nginx-debuginfo
nginx
nginx-help
nginx-source
nginx (Debian package)
compat-nginx-mod-stream
compat-nginx-mod-mail
compat-nginx-mod-http-xslt-filter
compat-nginx-mod-http-perl
compat-nginx-mod-http-image-filter
compat-nginx-debugsource
compat-nginx-all-modules
compat-nginx-filesystem
compat-nginx-help
compat-nginx-debuginfo
compat-nginx
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, 1.18.0-6ubuntu14.12, 1.24.0-2ubuntu7.9, 1.28.0-6ubuntu1.4, 1.28.3-2ubuntu1.2
nginx-mod-naxsi - addressed in versions 1.6-17.fc42, 1.6-17.fc43, 1.6-17.fc44
nginx-mod-devel - addressed in versions 1.21.5-12, 1.21.5-14, 1.24.0-10
nginx-filesystem - addressed in versions 1.21.5-12, 1.21.5-14, 1.24.0-10
nginx-all-modules - addressed in versions 1.21.5-12, 1.21.5-14, 1.24.0-10
nginx-mod-stream - addressed in versions 1.21.5-12, 1.21.5-14, 1.24.0-10
nginx-mod-mail - addressed in versions 1.21.5-12, 1.21.5-14, 1.24.0-10
nginx-mod-http-xslt-filter - addressed in versions 1.21.5-12, 1.21.5-14, 1.24.0-10
nginx-mod-http-perl - addressed in versions 1.21.5-12, 1.21.5-14, 1.24.0-10
nginx-mod-http-image-filter - addressed in versions 1.21.5-12, 1.21.5-14, 1.24.0-10
nginx-debugsource - addressed in versions 1.21.5-12, 1.21.5-14, 1.24.0-10
nginx-debuginfo - addressed in versions 1.21.5-12, 1.21.5-14, 1.24.0-10
nginx - addressed in versions 1.21.5-12, 1.21.5-14, 1.24.0-10
nginx-help - addressed in versions 1.21.5-14, 1.24.0-10
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 - addressed in versions 1.21.5-150400.3.20.1, 1.21.5-150600.10.18.1
nginx-source - 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-mod-stream - update to 1.24.0-10
compat-nginx-mod-mail - update to 1.24.0-10
compat-nginx-mod-http-xslt-filter - 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-all-modules - update to 1.24.0-10
compat-nginx-filesystem - update to 1.24.0-10
compat-nginx-help - update to 1.24.0-10
compat-nginx-debuginfo - update to 1.24.0-10
compat-nginx - update to 1.24.0-10
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

• https://my.f5.com/manage/s/article/K000161021

• 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
• Debian update for nginx
• SUSE 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
• openEuler 24.03 LTS SP3 update for nginx
• openEuler 24.03 LTS SP1 update for nginx
• Ubuntu update for nginx
• Ubuntu update for nginx
• SUSE update for nginx
• Gentoo update for nginx