{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata. Fed continuously.","feed_url":"https://feed.craftedsignal.io/tags/cve-2026-40366/feed.json","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cpes":[],"_cs_cves":[{"cvss":8.4,"id":"CVE-2026-40366"}],"_cs_exploited":false,"_cs_has_poc":false,"_cs_poc_references":[],"_cs_products":["Office Word"],"_cs_severities":["high"],"_cs_tags":["use-after-free","code-execution","cve-2026-40366"],"_cs_type":"advisory","_cs_vendors":["Microsoft"],"content_html":"\u003cp\u003eCVE-2026-40366 is a use-after-free vulnerability affecting Microsoft Office Word. This vulnerability allows an attacker with local access to execute arbitrary code. The vulnerability stems from improper memory management within the application, where a pointer to a freed memory region is dereferenced, leading to exploitable conditions. While the specific exploitation details are not available, the potential for arbitrary code execution makes this a high-severity vulnerability requiring immediate attention from security teams. The vulnerability was reported to Microsoft and assigned CVE-2026-40366.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003cp\u003eDue to the nature of use-after-free vulnerabilities and the lack of specific exploitation details, a generic attack chain is described below:\u003c/p\u003e\n\u003col\u003e\n\u003cli\u003eThe attacker crafts a malicious Word document with a specific structure triggering the memory corruption.\u003c/li\u003e\n\u003cli\u003eThe user opens the malicious document in Microsoft Office Word.\u003c/li\u003e\n\u003cli\u003eThe application processes the document, leading to the use-after-free condition.\u003c/li\u003e\n\u003cli\u003eThe attacker exploits the use-after-free vulnerability to overwrite a critical data structure in memory.\u003c/li\u003e\n\u003cli\u003eThe attacker gains control of the program execution flow.\u003c/li\u003e\n\u003cli\u003eThe attacker injects malicious code into the Word process.\u003c/li\u003e\n\u003cli\u003eThe injected code executes with the privileges of the Word process.\u003c/li\u003e\n\u003cli\u003eThe attacker achieves local code execution on the victim\u0026rsquo;s machine.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of CVE-2026-40366 allows an attacker to execute arbitrary code on the victim\u0026rsquo;s machine with the privileges of the Microsoft Office Word application. This can lead to complete system compromise, data theft, installation of malware, or other malicious activities. The vulnerability impacts any environment where vulnerable versions of Microsoft Office Word are used.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eApply the patch released by Microsoft to address CVE-2026-40366 as soon as possible (Reference: \u003ca href=\"https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40366)\"\u003ehttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-40366)\u003c/a\u003e.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule \u003ccode\u003eDetect Suspicious Word Process Creation\u003c/code\u003e to identify potential exploitation attempts (see rule below).\u003c/li\u003e\n\u003cli\u003eEnable process creation logging to provide the necessary data for the deployed Sigma rules (see rule logsource).\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-05-12T18:43:06Z","date_published":"2026-05-12T18:43:06Z","id":"https://feed.craftedsignal.io/briefs/2026-05-cve-2026-40366-word-uaf/","summary":"CVE-2026-40366 is a use-after-free vulnerability in Microsoft Office Word allowing local code execution by an unauthorized attacker.","title":"CVE-2026-40366: Microsoft Office Word Use-After-Free Vulnerability","url":"https://feed.craftedsignal.io/briefs/2026-05-cve-2026-40366-word-uaf/"}],"language":"en","title":"CraftedSignal Threat Feed — Cve-2026-40366","version":"https://jsonfeed.org/version/1.1"}