{"id":"CVE-2026-9256","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-9256","generatedAt":"2026-10-31T04:55:16.518Z","title":"NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module.","description":"NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when a rewrite directive uses a regex pattern with distinct, overlapping Perl-Compatible Regular Expression (PCRE) captures (for example, ^/((.*))$) and a replacement string that references multiple such captures (for example, $1$2) in a redirect or arguments context. 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\n\nNote: Software versions which have reached End of Technical Support (EoTS) are not evaluated.","published":"2026-05-22T15:16:27.000Z","lastModified":"2026-08-25T13:19:33.000Z","status":"Modified","sourceIdentifier":"f5sirt@f5.com","cvss":{"version":"4.0","score":9.2,"severity":"CRITICAL","vector":"CVSS:4.0/AV:N/AC:H/AT:P/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 open source","f5/nginx plus","f5/dos","f5/nginx gateway fabric","f5/nginx ingress controller","f5/nginx instance manager","f5/waf","redhat/discovery","redhat/hardened images","redhat/update infrastructure","debian/debian linux","redhat/enterprise linux"],"epss":{"score":0.10856,"percentile":0.95853,"date":"2026-10-30","history":[{"date":"2026-09-24","score":0.02697,"percentile":0.85289},{"date":"2026-10-25","score":0.10856,"percentile":0.95828}]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"urgent","text":"EPSS puts the probability of exploitation in the next 30 days at 10.9%, higher than 96% of all known CVEs. Patch or mitigate before the next change window."},"changes":[{"kind":"epss","label":"EPSS jump","at":"2026-10-25T00:00:00.000Z","detail":{"to":0.10856,"from":0.02697,"percentile":0.95828},"summary":"EPSS moved from 2.7% to 10.9% probability of exploitation in the next thirty days."}],"references":[{"url":"https://my.f5.com/manage/s/article/K000161377","tags":["Mitigation","Vendor Advisory"],"source":"f5sirt@f5.com"},{"url":"http://www.openwall.com/lists/oss-security/2026/05/22/14","tags":["Mailing List"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2026/06/msg00023.html","tags":["Mailing List","Third Party Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2026:20351","tags":["Third Party Advisory"],"source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:28212","tags":["Third Party Advisory"],"source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:28921","tags":["Third Party Advisory"],"source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:28973","tags":["Third Party Advisory"],"source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:29151","tags":["Third Party Advisory"],"source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:29874","tags":["Third Party Advisory"],"source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:33313","tags":["Third Party Advisory"],"source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:44481","tags":["Third Party Advisory"],"source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:58981","source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/security/cve/CVE-2026-9256","tags":["Third Party Advisory"],"source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2480746","tags":["Issue Tracking","Third Party Advisory"],"source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-9256.json","tags":["Third Party Advisory"],"source":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-9256","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."}