Loading story…
Microsoft published security guidance for multiple vulnerabilities in Windows Resilient File System (ReFS), including elevation-of-privilege issues tracked as CVE-2025-55687 and CVE-2026-23673. The company listed both flaws in its Security Update Guide, with CVE-2026-23673 appearing in both advisory and vulnerability entries, indicating coordinated documentation around the same ReFS privilege-escalation issue.
The disclosures also connect to an earlier remote code execution flaw in the same Windows component, CVE-2022-21892, showing that ReFS has been the subject of repeated security fixes across multiple years. Together, the references indicate ongoing Microsoft remediation for security weaknesses in the Windows file system layer that could allow attackers to gain higher privileges or, in the earlier case, execute code through ReFS-related attack paths.
See real exploitation activity before you spend the cycle.
3 events from the most recent confirmed update back to the earliest known activity.
Microsoft published Security Update Guide entries for CVE-2026-23673, describing it as a Windows Resilient File System (ReFS) elevation of privilege vulnerability. The advisory and vulnerability references appear to document the same disclosure event.
Microsoft added CVE-2025-55687 to its Security Update Guide as a Windows Resilient File System (ReFS) elevation of privilege vulnerability.
Microsoft published security guidance for CVE-2022-21892, a Windows Resilient File System (ReFS) remote code execution vulnerability.
See real exploitation activity behind this advisory so you can triage it against everything else in the queue.
4 references tracked. Mallory keeps watching after this page renders.
msrc.microsoft.com
Open sourcemsrc.microsoft.com
Open sourcemsrc.microsoft.com
Open sourceportal.msrc.microsoft.com
Open sourceMap indicators from this story to your assets and identify affected systems in minutes.
Every observed campaign, victim, and pivot linked to actors named in this story.
Malware, exploits, and IOCs connected to the activity described here.
YARA, Sigma, and Snort rules deployed to your SIEM as soon as they’re published.
Get matching new stories delivered to your team as they break — not the next morning.
Ask questions about this story and take action on the answers.
Other stories Mallory is tracking that overlap on entities, sources, or topic labels.
Microsoft published security advisories for a broad set of **remote code execution** vulnerabilities affecting Windows components and enterprise services, including **Windows Telephony Service**, **Hyper-V**, **ReFS**, **WSUS**, **Direct Show**, the **Windows Mobile Broadband Driver**, **Windows Server Setup and Boot Event Collection**, **SQL Server Native Client**, and **.NET**. The largest concentration of disclosures involved the Windows Telephony Service, with multiple CVEs including `CVE-2024-43620`, `CVE-2024-43627`, `CVE-2025-21190`, `CVE-2025-21240`, `CVE-2025-21243`, `CVE-2025-21250`, `CVE-2025-21266`, `CVE-2025-21273`, `CVE-2025-21409`, and `CVE-2025-21413`, indicating sustained patching activity around a single Windows attack surface. Other disclosed RCE issues expanded the risk to virtualization, storage, update infrastructure, and server environments through `CVE-2026-21244` and `CVE-2026-21248` in **Windows Hyper-V**, `CVE-2025-62456` in **Windows Resilient File System (ReFS)**, `CVE-2025-59287` in **Windows Server Update Service (WSUS)**, `CVE-2025-49666` in **Windows Server Setup and Boot Event Collection**, `CVE-2024-49012` in **SQL Server Native Client**, `CVE-2025-21291` in **Windows Direct Show**, and `CVE-2026-24288` in the **Windows Mobile Broadband Driver**. One referenced case, `CVE-2021-34458`, showed the potential severity of Microsoft RCE flaws in virtualized environments, with Microsoft describing a **Critical** Windows Kernel issue that could enable cross-guest interference on systems using **SR-IOV-capable hardware**.
Jun 29, 2026
Microsoft disclosed and patched multiple **elevation-of-privilege vulnerabilities** in the **Windows Common Log File System (CLFS) Driver**, including `CVE-2026-40407`, `CVE-2025-62470`, and `CVE-2025-32713`. The most detailed advisory, for `CVE-2026-40407`, describes a **heap-based buffer overflow** (`CWE-122`) that allows a locally authenticated low-privilege attacker to escalate to **SYSTEM** without user interaction. Microsoft rated `CVE-2026-40407` as **Important** with a **CVSS 3.1 score of 7.8**, citing **high** impact to confidentiality, integrity, and availability. The company said the flaw had **not** been publicly disclosed and was **not** being exploited in the wild at the time of publication, assessed exploitation as unlikely, and released an official security update to remediate the issue; the related CLFS advisories indicate a continuing pattern of privilege-escalation risk in this Windows component.
Jul 12, 2026
Microsoft published security advisories for several **elevation-of-privilege** vulnerabilities affecting Windows components and related software, including **Microsoft PC Manager** (`CVE-2025-21322`), **Windows Installer** (`CVE-2025-21331`, `CVE-2025-21373`), **Visual Studio** (`CVE-2025-49739`), **.NET** (`CVE-2025-55247`), **Windows Health and Optimized Experiences** (`CVE-2025-59241`), and **Host Process for Windows Tasks** (`CVE-2025-60710`). Microsoft also lists an earlier **Windows Storage** privilege-escalation issue, `CVE-2023-36399`, in its security guidance portal. The advisories provide limited public detail beyond product names and vulnerability class, but the grouping indicates broad exposure across both endpoint and developer environments where successful exploitation could allow an attacker to gain higher privileges on a target system. Organizations using affected Microsoft software should review the corresponding Security Update Guide entries, prioritize patch validation for Windows and developer-tooling assets, and assess whether privilege-escalation paths could be chained with other flaws or post-compromise activity.
Jul 12, 2026