{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata — refreshed continuously.","feed_url":"https://feed.craftedsignal.io/tags/cve-2026-31609/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cves":[{"id":"CVE-2026-31609"}],"_cs_exploited":false,"_cs_products":[],"_cs_severities":["critical"],"_cs_tags":["smb","double-free","cve-2026-31609","rce"],"_cs_type":"advisory","_cs_vendors":["Microsoft"],"content_html":"\u003cp\u003eCVE-2026-31609 is a double-free vulnerability affecting the SMB (Server Message Block) client. The vulnerability resides in the \u003ccode\u003esmbd_free_send_io()\u003c/code\u003e function, which is called after \u003ccode\u003esmbd_send_batch_flush()\u003c/code\u003e. A double-free vulnerability occurs when memory is freed twice, potentially leading to corruption of the heap and potentially allowing an attacker to execute arbitrary code. The specifics of exploitation are not detailed in the initial advisory but successful exploitation could lead to a complete compromise of the affected system. This vulnerability demands immediate attention from security teams due to the potential for remote code execution and the widespread use of the SMB protocol in networked environments.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAn attacker crafts a malicious SMB request designed to trigger the \u003ccode\u003esmbd_send_batch_flush()\u003c/code\u003e function within the SMB client.\u003c/li\u003e\n\u003cli\u003eThe \u003ccode\u003esmbd_send_batch_flush()\u003c/code\u003e function executes, processing the crafted SMB request.\u003c/li\u003e\n\u003cli\u003eDue to a flaw in the logic, the same memory is passed twice to a \u003ccode\u003efree()\u003c/code\u003e call within \u003ccode\u003esmbd_free_send_io()\u003c/code\u003e.\u003c/li\u003e\n\u003cli\u003eThe first \u003ccode\u003efree()\u003c/code\u003e call deallocates the memory as intended.\u003c/li\u003e\n\u003cli\u003eThe second \u003ccode\u003efree()\u003c/code\u003e call attempts to deallocate the already freed memory, causing a double-free condition.\u003c/li\u003e\n\u003cli\u003eThis double-free corrupts the heap metadata, creating an opportunity for an attacker to manipulate memory allocation.\u003c/li\u003e\n\u003cli\u003eThe attacker exploits the heap corruption to overwrite critical data structures within the SMB client process.\u003c/li\u003e\n\u003cli\u003eBy overwriting function pointers or other sensitive data, the attacker gains control of the execution flow, leading to arbitrary code execution.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of CVE-2026-31609 could allow an attacker to execute arbitrary code on the affected system with the privileges of the SMB client. Given the widespread use of SMB for file sharing and network communication, this vulnerability could be leveraged to gain unauthorized access to sensitive data, install malware, or disrupt critical services. The impact could range from data breaches and ransomware attacks to complete system compromise and lateral movement within a network.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eApply the security update provided by Microsoft to patch CVE-2026-31609 as soon as possible.\u003c/li\u003e\n\u003cli\u003eEnable SMB auditing to monitor for suspicious SMB traffic and potential exploitation attempts.\u003c/li\u003e\n\u003cli\u003eDeploy the following Sigma rule to detect potential exploitation attempts by monitoring for unusual SMB client process behavior.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2024-01-24T12:00:00Z","date_published":"2024-01-24T12:00:00Z","id":"/briefs/2024-01-24-smb-double-free/","summary":"CVE-2026-31609 is a critical double-free vulnerability in the SMB client, specifically within the smbd_free_send_io() function after smbd_send_batch_flush(), potentially leading to arbitrary code execution.","title":"CVE-2026-31609 SMB Client Double-Free Vulnerability","url":"https://feed.craftedsignal.io/briefs/2024-01-24-smb-double-free/"}],"language":"en","title":"CraftedSignal Threat Feed — Cve-2026-31609","version":"https://jsonfeed.org/version/1.1"}