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OpenAdvisories
High · 8.1 Public exploit CVE-2026-42533 EUVD-2026-44683GHSA-fxfg-v4rj-hp95

NGINX Map directive and Regex matching vulnerability

Published Jul 15, 2026 · Updated Nov 3, 2026 · Assigned by f5

Vendor: F5 Product: NGINX Open Source Product: NGINX Plus Package: ingress-nginx-controller-1.15 Package: nginx Package: nginx Package: nginx Package: nginx Package: nginx-mainline Package: nginx-stable Package: nginx-stable-package-config Category: Network devices Ecosystem: Alpine Ecosystem: Azure Linux Ecosystem: Debian Ecosystem: Ubuntu Ecosystem: Wolfi

Description

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.

Affected products

VendorProductAffectedFixed
F5 NGINX Plus 37.0.0.1 – < 37.0.3.1, R36 – < R36 P7, R33 37.0.3.1
F5 NGINX Open Source 1.31.2 – < 1.31.3, 0.9.6 – < 1.30.4 1.31.3

Fixed in Linux distributions

Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.

Debian

Security tracker ↗
ReleasePackageFixed inAdvisory
Debian 14 nginx 1.30.4-3 —
Debian 13 nginx 1.26.3-3+deb13u8 —
Debian 12 nginx 1.22.1-9+deb12u10 —

Ubuntu

Security tracker ↗
ReleasePackageFixed inAdvisory
Ubuntu 26.04 LTS nginx 1.28.3-2ubuntu1.11 USN-8563-5
Ubuntu 24.04 LTS nginx 1.24.0-2ubuntu7.18 USN-8563-5
Ubuntu 22.04 LTS nginx 1.18.0-6ubuntu14.21 USN-8563-5
Show 4 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Ubuntu Pro 20.04 LTS nginx 1.18.0-0ubuntu1.7+esm4 USN-8955-2
Ubuntu Pro 18.04 LTS nginx 1.14.0-0ubuntu1.11+esm5 USN-8955-2
Ubuntu Pro 16.04 LTS nginx 1.10.3-0ubuntu0.16.04.5+esm10 USN-8955-2
Ubuntu Pro 14.04 LTS nginx 1.4.6-1ubuntu3.9+esm9 USN-8955-2

Red Hat

Security tracker ↗
ReleasePackageFixed inAdvisory
RHEL 10 nginx +9 2:1.26.3-6.el10_2.7 RHSA-2026:67314
RHEL 9 nginx +9 1:1.24.0-7.module+el9.8.0+24846+e7eec568.5 RHSA-2026:67308, RHSA-2026:67283, RHSA-2026:66542
RHEL 8 nginx +8 1:1.24.0-3.module+el8.10.0+24848+0300f002.5 RHSA-2026:67315
Show 1 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
Red Hat Hardened Images 1 nginx +11 1.30.4-2.hum1 RHSA-2026:46012

AlmaLinux

Errata ↗
ReleasePackageFixed inAdvisory
AlmaLinux 10 nginx +9 2:1.26.3-6.el10_2.7 ALSA-2026:67314
AlmaLinux 9 nginx +9 1:1.24.0-7.module_el9.8.0+307+7a7a3a71.5.alma.1 ALSA-2026:67308, ALSA-2026:67283, ALSA-2026:66542
AlmaLinux 8 nginx +8 1:1.24.0-3.module_el8.10.0+4275+5756017d.5.alma.1 ALSA-2026:67315

Rocky Linux

Errata ↗
ReleasePackageFixed inAdvisory
Rocky Linux 10 nginx 2:1.26.3-6.el10_2.7 RLSA-2026:67314
Rocky Linux 9 nginx 1:1.24.0-7.module+el9.8.0+40193+7b2d11e4.1.rocky.0.1 RLSA-2026:67308, RLSA-2026:67283, RLSA-2026:66542
Rocky Linux 8 nginx 1:1.24.0-3.module+el8.10.0+40144+38158758 RLSA-2026:67315

SUSE

Security tracker ↗
ReleasePackageFixed inAdvisory
SLES 15 SP7 nginx 1.21.5-150600.10.27.1 SUSE-SU-2026:3469-1
SLES 15 SP6 nginx 1.21.5-150600.10.27.1 SUSE-SU-2026:3469-1
SLES 15 SP5 nginx 1.21.5-150400.3.25.1 SUSE-SU-2026:3448-1
SLES 15 SP4 nginx 1.21.5-150400.3.25.1 SUSE-SU-2026:3448-1
Show 7 more (older releases, extended support, other products)
ReleasePackageFixed inAdvisory
SLES for SAP 16.0 nginx 1.27.2-160000.7.1 SUSE-SU-2026:23140-1, SUSE-SU-2026:23118-1
SLES for SAP 15 SP6 nginx 1.21.5-150600.10.27.1 SUSE-SU-2026:3469-1
SLES for SAP 15 SP5 nginx 1.21.5-150400.3.25.1 SUSE-SU-2026:3448-1
SLES for SAP 15 SP4 nginx 1.21.5-150400.3.25.1 SUSE-SU-2026:3448-1
SLES 16.0 nginx 1.27.2-160000.7.1 SUSE-SU-2026:23140-1, SUSE-SU-2026:23118-1
SLE HPC 15 SP5 nginx 1.21.5-150400.3.25.1 SUSE-SU-2026:3448-1
SLE HPC 15 SP4 nginx 1.21.5-150400.3.25.1 SUSE-SU-2026:3448-1

openSUSE

Security tracker ↗
ReleasePackageFixed inAdvisory
openSUSE Tumbleweed nginx 1.31.3-1.1 openSUSE-SU-2026:11295-1
openSUSE Leap 16.0 nginx 1.27.2-160000.7.1 openSUSE-SU-2026:21524-1

Alpine

Security tracker ↗
ReleasePackageFixed inAdvisory
Alpine v3.24 nginx 1.30.4-r0 —
Alpine v3.23 nginx 1.28.3-r6 —
Alpine v3.22 nginx 1.28.3-r6 —
Alpine v3.21 nginx 1.26.3-r2 —

Amazon Linux

ReleasePackageFixed inAdvisory
Amazon Linux 2023 nginx +9 1:1.30.4-1.amzn2023.0.1 ALAS2023-2026-2008

Azure Linux

ReleasePackageFixed inAdvisory
Azure Linux 3 nginx 1.28.3-8 —

Wolfi

ReleasePackageFixed inAdvisory
Wolfi rolling ingress-nginx-controller-1.15 1.15.10-r0 —
Wolfi rolling nginx-mainline 1.31.3-r0 —
Wolfi rolling nginx-stable 1.30.4-r0 —
Wolfi rolling nginx-stable-package-config 1.30.4-r5 —

Public exploits

Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.

Third-party code, not reviewed by us. Public PoCs are sometimes fake or contain malware. Read the code first and run it only in an isolated lab, against systems you are authorised to test.

GitHub 12 repositories · most starred shown

Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.

Advisories 26

References