CVE-2026-42533
critical · 9.2A 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.
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
Weaknesses
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| f5 | nginx_gateway_fabric | >= 1.3.0, <= 1.6.2 |
| f5 | nginx_gateway_fabric | >= 2.0.0, < 2.6.7 |
| f5 | nginx_ingress_controller | >= 3.5.0, <= 3.7.2 |
| f5 | nginx_ingress_controller | >= 5.0.0, < 5.5.3 |
| 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 | >= r33, < 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 | nginx_plus | r36 |
| f5 | waf | >= 4.11.0, <= 4.16.0 |
| f5 | waf | >= 5.2.0, <= 5.8.0 |
| f5 | waf | >= 5.9.0, < 5.13.4 |
Check a specific version with /api/v1/cve/match.
References
Query this programmatically:
curl https://evil-db.io/api/v1/cve/CVE-2026-42533