CVE-2026-3842 (CVSS 7.8 High) is a local privilege escalation vulnerability in QEMU-KVM's Hyper-V synthetic debug device where a missing bounds check after `cpu_physical_memory_map` leads to a host out-of-bounds write. This allows a local attacker with guest-level privileges to potentially execute arbitrary code on the host. The article does not provide specific affected or fixed version information.
We use optional cookies to improve your experience on our websites, such as through social media connections, and to display personalized advertising based on your online activity. If you reject optional cookies, only cookies necessary to provide you the services will be used. You may change your selection by clicking โManage Cookiesโ at the bottom of the page. Privacy Statement Third-Party Cookies AcceptRejectManage cookies MSRC ๎ฌ Customer Guidance ๎ฌ Security Update Guide ๎ฌ Vulnerabilities ๎ฌ CVE-2026-3842 Qemu-kvm: hyperv/syndbg: missing mapped-length guard after cpu_physical_memory_map causes host oob write NewRecently updated On this page ๎ CVE-2026-3842 ๎ Subscribe RSS PowerShell ๎ฅ API ๎ฅ CSAF Security Vulnerability Released: Jul 19, 2026 Last updated: Jul 21, 2026 Assigning CNA fedora CVE.org link CVE-2026-3842 ๏ Weakness CWE-787: Out-of-bounds Write CVSS Source fedora Vector String CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Metrics CVSS:3.1 7.8 / 7.8 ๎ฅ Base score metrics: 7.8 / Temporal score metrics: 7.8 ๎ฅฎ Expand all ๎ฅฐ Collapse all Metric Value ๎ฃฌ ๎ฅด Base score metrics(8) Attack Vector Local Attack Complexity Low Privileges Required Low User Interaction None Scope Unchanged Confidentiality High Integrity High Availability High Please see Common Vulnerability Scoring System for more information on the definition of these metrics. Acknowledgements Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure. See Acknowledgements for more information. Security Updates To determine the support lifecycle for your software, see the Microsoft Support Lifecycle. Release date Descending ๎ Edit columns ๎ข Download ๎ Filters ๎ก Product Family ๎ Max Severity ๎ Impact ๎ Platform ๎ ๎ข Clear Release date ๎นฉ Product Platform Impact Max Severity Article Download Build Number Assigning CNA Loading... Disclaimer The information provided in the Microsoft Knowledge Base is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply. Revisions version revisionDate description 3.0 Jul 21, 2026 Information published. 2.0 Jul 20, 2026 Information published. 1.0 Jul 19, 2026 Information published. ๎น How satisfied are you with the MSRC Security Update Guide? Rating ๎ Broken ๎ช Bad ๎ Below average ๎ช Average ๎ฎ Great! ๎ข Your Privacy Choices Consumer Health Privacy Privacy & Cookies