CVE-2026-42533A 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 out…
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It affects f5 nginx_gateway_fabric and 3 other products. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 8.1 HIGH (v3.1, NVD)CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- CWE-122
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Analyzed
- Record last updated
- Aug 10, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
f5 nginx_gateway_fabric f5:nginx_gateway_fabric | from 1.3.0 through 1.6.2; from 2.0.0 before 2.6.7 | NVD |
f5 nginx_ingress_controller f5:nginx_ingress_controller | from 3.5.0 through 3.7.2; from 5.0.0 before 5.5.3; from 2026-lts-r1 before 2026-lts-r4; 4.0.0; 4.0.1 | NVD |
f5 nginx_plus f5:nginx_plus | from 37.0.0.1 before 37.0.3.1; from r33 before r36; r36; r36; r36; r36; r36; r36; and 1 more ranges | NVD |
f5 waf f5:waf | from 4.11.0 through 4.16.0; from 5.2.0 through 5.8.0; from 5.9.0 before 5.13.4 | NVD |
References
- https://my.f5.com/manage/s/article/K000162097vendor-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.