Here’s what Microsoft fixed in September’s Patch Tuesday

CVE-2024-38014 is an elevation-of-privilege flaw caused by improper privilege management (CWE-269) in the Microsoft Windows Installer component, rated 7.8 (high) with a local attack vector, low privileges required, and no user interaction. An attacker who already has limited access and can execute code on a targeted machine can trigger the vulnerable Installer behavior to gain elevated privileges, with high impact on the confidentiality, integrity, and availability of the host. The flaw affects the listed Windows 10, Windows 11, and Windows Server versions (CISA describes the affected product simply as 'Microsoft Windows', so other versions may also be impacted). It was fixed as part of Microsoft's September 2024 Patch Tuesday, which addressed 79 flaws including four actively exploited zero-days, and Microsoft's advisories plus CISA's KEV entry (added 2024-09-10) confirm it is being exploited in the wild; no public proof-of-concept is known and ransomware association is unknown. Its EPSS score of 6.3% (93rd percentile) is unusually high for a local privilege escalation, so Windows fleets should treat this as a priority patch.

Do: Apply Microsoft's September 2024 security updates (or any later cumulative update) for the affected Windows 10, Windows 11, and Windows Server versions, prioritizing servers and multi-user systems where untrusted local code runs; because this flaw is KEV-listed and actively exploited, remediation should follow CISA's vendor-instruction requirement. Given September 2024 reporting that a servicing defect left some Windows PCs unpatched despite appearing updated, verify via Windows Update history or your patch-management tooling that the cumulative update actually installed. No workaround is specified in the available data, so patching is the primary mitigation.

CVE-2024-38226 is a security feature bypass (protection mechanism failure, CWE-693) in Microsoft Publisher, rated 7.3 High with a local attack vector, low privileges required, and user interaction required. An attacker triggers it by convincing a user to open a maliciously crafted Publisher file, which defeats Publisher's built-in protection mechanism, allowing the attacker's content to bypass the expected security checks, with high impact rated for confidentiality, integrity, and availability. Users of Publisher as shipped in Microsoft Office 2019 and Microsoft Office Long Term Servicing Channel (LTSC) are affected. The flaw was patched in Microsoft's September 2024 Patch Tuesday, counted among the four actively exploited Microsoft zero-days that month, and CISA added it to the Known Exploited Vulnerabilities catalog on 2024-09-10, confirming exploitation in the wild; ransomware use is listed as unknown.

Do: Apply the September 2024 Microsoft security updates for Office 2019/LTSC (Publisher) across all endpoints, prioritizing systems with Publisher installed, per the vendor's instructions or the CISA KEV required action. Until patched, warn users to exercise caution with .pub files from untrusted sources, since exploitation requires opening a crafted file. Confirm no Publisher clients remain on outdated builds after deployment.

Microsoft is aware of a vulnerability in Servicing Stack that has rolled back the fixes for some vulnerabilities affecting Optional Components on Windows 10, version 1507 (initial version released July 2015). This means that an attacker could exploit these previously mitigated vulnerabilities on Windows 10, version 1507 (Windows 10 Enterprise 2015 LTSB and Windows 10 IoT Enterprise 2015 LTSB) systems that have installed the Windows security update released on March 12, 2024—KB5035858 (OS Build 10240.20526) or other updates released until August 2024. All later versions of Windows 10 are not impacted by this vulnerability. This servicing stack vulnerability is addressed by installing the September 2024 Servicing stack update (SSU KB5043936) AND the September 2024 Windows security update (KB5043083), in that order. Note: Windows 10, version 1507 reached the end of support (EOS) on May 9, 2017 for devices running the Pro, Home, Enterprise, Education, and Enterprise IoT editions. Only Windows 10 Enterprise 2015 LTSB and Windows 10 IoT Enterprise 2015 LTSB editions are still under support.