{"id":"CVE-2026-42533","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-42533","generatedAt":"2026-10-28T00:08:07.750Z","title":"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.","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.\n\nImpact:\nThis 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.\n\n\n\n\n Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.","published":"2026-07-15T15:16:33.000Z","lastModified":"2026-08-10T15:28:02.000Z","status":"Analyzed","sourceIdentifier":"f5sirt@f5.com","cvss":{"version":"4.0","score":9.2,"severity":"CRITICAL","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/M"},"cwe":["CWE-122"],"affected":["f5/nginx gateway fabric","f5/nginx ingress controller","f5/nginx plus","f5/waf"],"epss":{"score":0.00894,"percentile":0.59233,"date":"2026-10-26","history":[{"date":"2026-09-24","score":0.00894,"percentile":0.57748}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.89%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://my.f5.com/manage/s/article/K000162097","tags":["Vendor Advisory"],"source":"f5sirt@f5.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-42533","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}