{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata — refreshed continuously.","feed_url":"https://feed.craftedsignal.io/tags/cve-2026-31611/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cves":[{"id":"CVE-2026-31611"}],"_cs_exploited":false,"_cs_products":[],"_cs_severities":["high"],"_cs_tags":["cve-2026-31611","ksmbd","smb","vulnerability"],"_cs_type":"advisory","_cs_vendors":["Microsoft"],"content_html":"\u003cp\u003eCVE-2026-31611 is a newly disclosed security vulnerability affecting ksmbd, a kernel-based SMB server. The vulnerability stems from insufficient validation of sub-authorities within the ksmbd code, specifically requiring at least three sub-authorities before reading sub_auth[2]. While the exact exploitation details remain undisclosed in the initial advisory, the nature of the flaw suggests a potential for memory corruption or out-of-bounds read, which could be leveraged by attackers to achieve unauthorized access or potentially execute arbitrary code within the context of the ksmbd kernel module. This vulnerability poses a significant risk to systems utilizing ksmbd for file sharing, particularly if exposed to untrusted networks. The initial publication of the CVE was on 2026-04-26, but this brief serves as an early warning for detection engineers.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003cp\u003eSince the specific exploitation details of CVE-2026-31611 are not yet publicly available, the following attack chain is a hypothetical scenario based on the nature of the vulnerability:\u003c/p\u003e\n\u003col\u003e\n\u003cli\u003eAttacker identifies a target system running a vulnerable version of ksmbd.\u003c/li\u003e\n\u003cli\u003eThe attacker crafts a malicious SMB request specifically designed to trigger the sub-authority validation flaw.\u003c/li\u003e\n\u003cli\u003eThe SMB request is sent to the target system\u0026rsquo;s ksmbd service over port 445.\u003c/li\u003e\n\u003cli\u003eThe ksmbd service receives the malicious request and processes the sub-authority data.\u003c/li\u003e\n\u003cli\u003eDue to the insufficient validation, the code attempts to read \u003ccode\u003esub_auth[2]\u003c/code\u003e without ensuring at least three sub-authorities are present.\u003c/li\u003e\n\u003cli\u003eThis leads to an out-of-bounds read, potentially leaking sensitive information or causing a crash.\u003c/li\u003e\n\u003cli\u003eAn attacker might be able to leverage this out-of-bounds read to overwrite memory, potentially leading to arbitrary code execution within the kernel.\u003c/li\u003e\n\u003cli\u003eSuccessful exploitation could grant the attacker elevated privileges on the system, enabling them to install malware, exfiltrate data, or disrupt services.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of CVE-2026-31611 could allow an attacker to gain unauthorized access to sensitive data, execute arbitrary code within the kernel, and potentially compromise the entire system. The impact is particularly severe for systems acting as file servers, as they often hold critical data and are relied upon by multiple users. While the number of potential victims is currently unknown, any system running a vulnerable version of ksmbd is at risk. This could lead to data breaches, financial losses, and reputational damage.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eMonitor network traffic for SMB requests that may be attempting to exploit the vulnerability, using a network intrusion detection system (NIDS) or firewall logs. Analyze SMB requests for unusual patterns or malformed sub-authority data (network_connection).\u003c/li\u003e\n\u003cli\u003eImplement detections for unusual process execution originating from the ksmbd process, as successful exploitation could lead to arbitrary code execution (process_creation).\u003c/li\u003e\n\u003cli\u003eDeploy the provided Sigma rule to detect potential exploitation attempts based on suspicious SMB activity (rules).\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2024-01-24T12:00:00Z","date_published":"2024-01-24T12:00:00Z","id":"/briefs/2024-01-cve-2026-31611-ksmbd/","summary":"CVE-2026-31611 is a vulnerability in ksmbd, requiring at least three sub-authorities before reading sub_auth[2], potentially leading to unauthorized access or code execution.","title":"CVE-2026-31611: ksmbd Sub-Authority Validation Vulnerability","url":"https://feed.craftedsignal.io/briefs/2024-01-cve-2026-31611-ksmbd/"}],"language":"en","title":"CraftedSignal Threat Feed — Cve-2026-31611","version":"https://jsonfeed.org/version/1.1"}