Sept 2025 Patch Tuesday Updates

As cybersecurity threats continue to evolve, September’s patch cycle brings critical updates across Microsoft, Adobe, and browser platforms. This month’s releases address vulnerabilities that range from remote code execution to privilege escalation, with implications for both enterprise and personal systems.

Microsoft Patch Tuesday – September 2025

Microsoft released 81 security fixes, including two publicly disclosed zero-day vulnerabilities:

Key Vulnerabilities

• CVE-2025-55234 – Windows SMB Elevation of Privilege: Exploitable via relay attacks. Microsoft recommends enabling SMB signing and Extended Protection for Authentication (EPA), though these may cause compatibility issues with legacy systems.
• CVE-2024-21907 – SQL Server Denial of Service: Caused by a flaw in the Newtonsoft.Json library. Crafted data can trigger a StackOverflow exception.bleepingcomputer

Other Critical Fixes

• Remote Code Execution (RCE) flaws in Microsoft Office, Windows NTFS, and Graphics Kernel.
• Elevation of Privilege vulnerabilities in Azure, Hyper-V, and BitLocker.
• Security Feature Bypass in Microsoft Edge (CVE-2025-53791).bleepingcomputer

Risks of Not Installing

• Exposure to credential theft, malware injection, and data exfiltration.
• Increased risk of phishing campaigns leveraging unpatched SMB and Office vulnerabilities.

Risks of Installing

• Potential compatibility issues with older SMB clients when enabling hardening features.
• Updates may cause performance degradation in specific enterprise setups if not tested properly.

Adobe Security Updates – Acrobat & Reader

Adobe released updates for Acrobat DC, Reader DC, and Classic 2020/2024 tracks for Windows and macOS.

Key Vulnerabilities

• CVE-2025-54257 – Use-After-Free: Critical flaw allowing arbitrary code execution.
• CVE-2025-54255 – Security Feature Bypass: Moderate severity.adobe

Affected Versions

• Acrobat/Reader DC: Versions prior to 25.001.20693
• Acrobat 2020/2024: Versions prior to 20.005.30793 / 24.001.30264

Risks of Not Installing

• Potential for remote code execution via malicious PDF files.
• Risk of security feature bypass, undermining sandboxing and document integrity.

Risks of Installing

• Minimal, as Adobe reports no known exploits in the wild and updates are categorized as Priority 3 (routine deployment).adobe

Browser Updates – Chrome & Edge

Chrome 140 & Edge 140.0.3485.54

Both browsers patched a high-severity vulnerability in the V8 JavaScript engine:

• CVE-2025-9864 – Use-After-Free in V8: Allows memory corruption and potential remote code execution via crafted web pages.windowsforum

Other Fixes

• Toolbar, Extensions, and Downloads vulnerabilities (medium severity).
• Microsoft-specific fix in Edge: CVE-2025-53791 – Security Feature Bypass.techepages

Risks of Not Installing

• Exposure to drive-by attacks, malvertising, and phishing.
• Potential for sandbox escape and full system compromise in chained exploits.

Risks of Installing

• Possible extension compatibility issues.
• Minor performance changes due to updated sandboxing and memory handling.

What You Should Do

• Test updates in staging environments before full deployment.
• Enable auditing for SMB and Office components to detect compatibility issues.
• Update browsers immediately, especially in high-risk environments.
• Apply Adobe updates via managed deployment tools for enterprise consistency.

Security Best Practices

• Use Content Security Policies (CSP) and Enhanced Safe Browsing.
• Monitor for anomalous browser behavior and renderer crashes.
• Apply network-level protections to block malicious domains.

If you need any further details of this months releases or advise / guidance on their deployment please contact us on 01246 901392 or Info@securechaingroup.com