{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/tags/cve-2026-9256/feed.json","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cpes":[],"_cs_cves":[],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["NGINX Open Source","NGINX Plus"],"_cs_severities":["critical"],"_cs_tags":["nginx","rce","dos","CVE-2026-9256","webserver"],"_cs_type":"advisory","_cs_vendors":["nginx","F5"],"content_html":"\u003cp\u003eA critical vulnerability has been identified in Nginx, potentially allowing for remote code execution (RCE) and denial-of-service (DoS) attacks. This flaw impacts a range of Nginx versions, specifically Nginx Open Source versions 1.x prior to 1.30.2, versions later than 1.31.0 but before 1.31.1, Nginx Plus versions 37.x before 37.0.1.1, and Nginx Plus versions Rx before R36 P5 or R32 P7. According to the vendor, Nginx Open Source versions 0.x will not receive patches. This vulnerability, tracked as CVE-2026-9256, poses a significant risk to systems running affected Nginx versions, potentially enabling attackers to gain unauthorized access or disrupt service availability. Defenders should apply patches immediately.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eThe attacker identifies a vulnerable Nginx instance exposed to the internet.\u003c/li\u003e\n\u003cli\u003eThe attacker crafts a malicious HTTP request specifically designed to exploit the CVE-2026-9256 vulnerability.\u003c/li\u003e\n\u003cli\u003eThe crafted request is sent to the vulnerable Nginx server.\u003c/li\u003e\n\u003cli\u003eNginx processes the malicious request, triggering the vulnerability.\u003c/li\u003e\n\u003cli\u003eThe vulnerability leads to arbitrary code execution within the context of the Nginx worker process.\u003c/li\u003e\n\u003cli\u003eThe attacker executes shell commands to install a persistent backdoor.\u003c/li\u003e\n\u003cli\u003eAlternatively, the attacker can cause a denial of service by triggering a crash within the Nginx worker process.\u003c/li\u003e\n\u003cli\u003eThe attacker gains full control of the compromised server or disrupts the availability of the web service.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of CVE-2026-9256 can lead to complete compromise of the Nginx server, allowing attackers to execute arbitrary commands, access sensitive data, or use the server as a pivot point for further attacks within the network. The vulnerability also allows for denial-of-service attacks, causing disruption of services and potential financial losses. The scope of impact depends on the role of the Nginx server within the infrastructure, but could affect numerous organizations using the listed versions.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eImmediately patch Nginx to the latest version as indicated in the F5 security bulletin K000161377 to remediate CVE-2026-9256.\u003c/li\u003e\n\u003cli\u003eMonitor web server logs for suspicious activity and HTTP requests targeting CVE-2026-9256 (see example Sigma rules).\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rules provided to detect exploitation attempts against Nginx.\u003c/li\u003e\n\u003cli\u003eReview and harden Nginx configurations based on vendor best practices.\u003c/li\u003e\n\u003cli\u003eConsult the F5 security bulletin K000161377 for specific upgrade instructions.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-05-26T13:14:56Z","date_published":"2026-05-26T13:14:56Z","id":"https://feed.craftedsignal.io/briefs/2026-05-nginx-rce-dos/","summary":"A vulnerability in Nginx allows a remote attacker to execute arbitrary code and cause a denial-of-service condition, affecting Nginx Open Source versions 1.x before 1.30.2, versions after 1.31.0 before 1.31.1, Nginx Plus versions 37.x before 37.0.1.1, and versions Rx before R36 P5 or R32 P7.","title":"Nginx Vulnerability Leading to Remote Code Execution and Denial of Service","url":"https://feed.craftedsignal.io/briefs/2026-05-nginx-rce-dos/"}],"language":"en","title":"CraftedSignal Threat Feed — CVE-2026-9256","version":"https://jsonfeed.org/version/1.1"}