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Microsoft disclosed CVE-2026-72971, an Important tampering vulnerability in the Windows Container Isolation FS Filter Driver (unionfs.sys). The flaw stems from improper link resolution before file access, mapped to CWE-59, and could allow a locally authorized attacker with low privileges to modify or redirect file operations without user interaction. Microsoft assigned the issue a CVSS v3.1 score of 5.5, said exploitation was less likely, and noted the vulnerability had been publicly disclosed but was not known to be exploited at publication.
CWE-59, commonly known as link following, covers cases where software accesses a file path without ensuring it does not resolve to an unintended symbolic link, hard link, shortcut, or similar target. MITRE notes that such weaknesses can enable unauthorized file reads, file modification, protection bypass, and in some cases code execution, particularly when combined with predictable filenames, race conditions, or non-atomic file handling. Microsoft released a fix for the unionfs.sys issue alongside the advisory.
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Microsoft published an advisory for CVE-2026-72971, a CWE-59 tampering vulnerability in the Windows Container Isolation FS Filter Driver (unionfs.sys) that allows a low-privileged local attacker to perform tampering. Microsoft said the issue had been publicly disclosed, was not exploited at publication time, and that an official fix was available.
MITRE published the CWE-59 entry for "Improper Link Resolution Before File Access ('Link Following')" and classified it as a Base-level weakness that can be mapped to real-world vulnerabilities.
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Red Hat disclosed **CVE-2026-50526**, a moderate-severity flaw in **.NET** caused by improper link resolution before file access, tracked as **`CWE-59`**. The vulnerability allows an authorized local attacker to exploit link following behavior to tamper with files, potentially modifying application data or system files outside the intended target. Red Hat assigned the issue a **CVSS v3 score of 7.0**, while the NVD scored it **5.5**, reflecting different assessments of the flaw's impact. The weakness matches the broader **link following** class in which software accesses a file path without preventing resolution through symlinks, hard links, shortcuts, or similar mechanisms, creating opportunities for unauthorized read or write operations. Red Hat reported fixes across multiple **RHEL 8, 9, and 10** product lines, including specialized support channels such as **RHEL 10.0 EUS**, **RHEL 9.4 Update Services for SAP Solutions**, and **RHEL 9.6 EUS**, with remediation delivered through RHSA advisories published in July and August 2026.
Aug 24, 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 updates for multiple Windows elevation-of-privilege vulnerabilities affecting **Windows Shell**, **Windows User Interface Core**, and **Windows File Explorer**, including `CVE-2026-27918`, `CVE-2026-27911`, `CVE-2025-64661`, and `CVE-2025-64658`. The issues could allow attackers to gain higher privileges on a vulnerable system after obtaining local access, extending a pattern of privilege-escalation risk across core Windows components. Microsoft provided the most detail for **`CVE-2026-27911`**, which it rated **Important** with a **CVSS 3.1 score of 7.8**. The flaw stems from a **race condition** and **use-after-free** weakness in Windows User Interface Core and can be exploited by a low-privileged local attacker without user interaction. Successful exploitation could let an attacker escape a contained environment such as an **AppContainer**, raising privileges from **Low Integrity Level** to **Medium Integrity Level**. Microsoft said exploitation requires winning a race condition, assessed exploitation as unlikely at publication, and reported that the vulnerability had neither been publicly disclosed nor exploited before fixes were released.
Jul 12, 2026