CVE-2026-42533

CVE Enrichment

CVSS: 9.2 CRITICAL
EPSS: 0.89%
EPSS Percentile: 58.75%
CISA KEV: Not listed

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.

Technical Details

CVSS Version: 4.0
CNA / NVD Source: f5sirt@f5.com
Published: 15-Jul-2026 22:16
Last Modified: 10-Aug-2026 22:28
EPSS Date: 2026-10-16
CWE: CWE-122

CVSS 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 /
                            E:X /
                            CR:X /
                            IR:X /
                            AR:X /
                            MAV:X /
                            MAC:X /
                            MAT:X /
                            MPR:X /
                            MUI:X /
                            MVC:X /
                            MVI:X /
                            MVA:X /
                            MSC:X /
                            MSI:X /
                            MSA:X /
                            S:X /
                            AU:X /
                            R:X /
                            V:X /
                            RE:X /
                            U:X

Affected Products / Versions

f5 / nginx_gateway_fabric
Version / affected range: * · from (inclusive) 1.3.0 · through (inclusive) 1.6.2
cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:*
f5 / nginx_gateway_fabric
Version / affected range: * · from (inclusive) 2.0.0 · before (exclusive) 2.6.7
cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:*
f5 / nginx_ingress_controller
Version / affected range: * · from (inclusive) 3.5.0 · through (inclusive) 3.7.2
cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:continuous_releases:*:*:*
f5 / nginx_ingress_controller
Version / affected range: * · from (inclusive) 5.0.0 · before (exclusive) 5.5.3
cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:continuous_releases:*:*:*
f5 / nginx_ingress_controller
Version / affected range: * · from (inclusive) 2026-lts-r1 · before (exclusive) 2026-lts-r4
cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:long-term_support:*:*:*
f5 / nginx_ingress_controller
Version / affected range: 4.0.0
cpe:2.3:a:f5:nginx_ingress_controller:4.0.0:*:*:*:continuous_releases:*:*:*
f5 / nginx_ingress_controller
Version / affected range: 4.0.1
cpe:2.3:a:f5:nginx_ingress_controller:4.0.1:*:*:*:continuous_releases:*:*:*
f5 / nginx_plus
Version / affected range: * · from (inclusive) 37.0.0.1 · before (exclusive) 37.0.3.1
cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:*
f5 / nginx_plus
Version / affected range: * · from (inclusive) r33 · before (exclusive) r36
cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:*
f5 / nginx_plus
Version / affected range: r36
cpe:2.3:a:f5:nginx_plus:r36:-:*:*:*:*:*:*
f5 / nginx_plus
Version / affected range: r36
cpe:2.3:a:f5:nginx_plus:r36:p1:*:*:*:*:*:*
f5 / nginx_plus
Version / affected range: r36
cpe:2.3:a:f5:nginx_plus:r36:p2:*:*:*:*:*:*
f5 / nginx_plus
Version / affected range: r36
cpe:2.3:a:f5:nginx_plus:r36:p3:*:*:*:*:*:*
f5 / nginx_plus
Version / affected range: r36
cpe:2.3:a:f5:nginx_plus:r36:p4:*:*:*:*:*:*
f5 / nginx_plus
Version / affected range: r36
cpe:2.3:a:f5:nginx_plus:r36:p5:*:*:*:*:*:*
f5 / nginx_plus
Version / affected range: r36
cpe:2.3:a:f5:nginx_plus:r36:p6:*:*:*:*:*:*
f5 / waf
Version / affected range: * · from (inclusive) 4.11.0 · through (inclusive) 4.16.0
cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:*
f5 / waf
Version / affected range: * · from (inclusive) 5.2.0 · through (inclusive) 5.8.0
cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:*
f5 / waf
Version / affected range: * · from (inclusive) 5.9.0 · before (exclusive) 5.13.4
cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:*

References

f5sirt@f5.com

Last enrichment sync: 17-Oct-2026 08:46
Sources: NVD · FIRST EPSS · CISA KEV
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Reported Context (1)

The map flaw, CVE-2026-93479, is in the string-handling code that NGINX patched on July 15 for CVE-2026-42533, a heap overflow F5 scored 9.2 that is reached through a regex map's captures. NGINX Fixes Five Flaws, Including Possible Code Execution and TLS Client-Certificate Bypass

CVE (2)

People (5)

Vendors (1)

Products (7)

Tools (3)

Note: Related entities, including threat actors, malware, CVEs, MITRE ATT&CK techniques, vendors, products, tools, countries, and industries, are shown when they appear in the same reporting. Their presence does not necessarily mean they were targeted, compromised, vulnerable, responsible for the activity, or directly involved in the incident.