CVE-2026-42533
CRITICAL 12 PoCsAttack Surface
CVSS Vector Breakdown
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.
Weakness Classification (1)
Affected Software (19)
| Vendor | Product | Version |
|---|---|---|
| F5 | NGINX Open Source | 1.31.2 < 1.31.3 |
| F5 | NGINX Open Source | 0.9.6 < 1.30.4 |
| F5 | NGINX Plus | 37.0.0.1 < 37.0.3.1 |
| F5 | NGINX Plus | R36 < R36 P7 |
| F5 | NGINX Plus | R33 < * |
| f5 | nginx_gateway_fabric | 1.3.0 – 1.6.2 |
| f5 | nginx_ingress_controller | 3.5.0 – 3.7.2 |
| f5 | nginx_ingress_controller | 2026-lts-r1 – 2026-lts-r4 |
| f5 | nginx_ingress_controller | 4.0.0 |
| f5 | nginx_ingress_controller | 4.0.1 |
| f5 | nginx_plus | 37.0.0.1 – 37.0.3.1 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r36 |
| f5 | waf | 4.11.0 – 4.16.0 |