Top 10 Cybersecurity Vulnerabilities in 2025—and Why They Still Matter

If 2024 was the year of the “identity attack,” 2025 was the year the perimeter officially collapsed. In the last twelve months, we witnessed a ruthless optimization of the exploit lifecycle. Attackers didn’t just find bugs; they operationalized them into automated kill chains within hours of disclosure. 

For IT and security leaders, the lesson of 2025 is stark: the “patch within 30 days” standard is obsolete. The vulnerabilities that defined this year targeted the very appliances meant to secure us—VPNs, firewalls, and identity providers—and struck at the very code frameworks that power the modern web. 

Based on active exploitation data, business impact, and structural severity, here are the top 10 cybersecurity vulnerabilities of 2025 that every organization must address immediately. 

Ivanti Connect Secure: The “Zombie” Edge Flaw 

CVE-2025-22457 | Critical Stack-Based Buffer Overflow 

• The Vulnerability:A devastating remote code execution (RCE) flaw in Ivanti Connect Secure (VPN) gateways. It allowedunauthenticated attackers to execute arbitrary commands by overflowing a stack buffer. 
• The 2025 Impact:Thiswasn’t just a breach; it was a siege. Attributed to suspected China-nexus actors, this vulnerability was exploited as a zero-day to drop sophisticated webshells. What made it unique in 2025 was the attackers’ ability to bypass built-in Integrity Checker Tools (ICT), effectively hiding their presence even after patches were applied. 
• Why It Still Matters:Edge devices are notoriously difficult to patch without causing business downtime. Many organizations applied the patch butfailed to perform the necessary “factory reset” to clear persistent backdoors. If you run Ivanti gateways, a simple version check is insufficient—forensic verification is required. 

Microsoft SharePoint “ToolShell”: The On-Premise Nightmare 

CVE-2025-53770 | Unauthenticated RCE via Deserialization 

• The Vulnerability:A 9.8 CVSS critical flaw inon-premise SharePoint Servers (2016/2019). It allowed attackers to send crafted requests that triggered the deserialization of untrusted data, granting full system control. 
• The 2025 Impact:Dubbed the “ToolShell” campaign, this vulnerability became a favorite of Initial Access Brokers (IABs). Because SharePoint servers often sitdeep inside internal networks with “SYSTEM” privileges, compromising one effectively gave attackers the keys to the entire internal kingdom. 
• Why It Still Matters:On-premiseSharePoint is “legacy debt” for many enterprises—often forgotten, rarely updated, and critical to operations. Attackers know this. They are still scanning for unpatched internal SharePoint instances to use as silent staging grounds for ransomware. 

Citrix NetScaler: The Infrastructure Open Door 

CVE-2025-7775 | Memory Overflow RCE 

• The Vulnerability:A memory overflow vulnerability in NetScaler ADC and Gateway. It allowed unauthenticated adversaries to crash the service or, more dangerously, execute code remotely.
• The 2025 Impact:August 2025 saw a wave of attacks targeting critical infrastructure using this flaw. Unlike user-facing bugs, this targeted the traffic controllers of the enterprise network.
• Why It Still Matters:NetScaler appliances are critical to application delivery. Taking them offline for patching is a logistical nightmare for 24/7 operations, leading to “patch paralysis.” VulnerableNetScalers remain one of the highest-value targets for nation-state actors looking for long-term espionage persistence. 

Fortinet Suite: The “Everything is a Firewall” Risk 

CVE-2025-32756 | Stack-Based Buffer Overflow (Multiple Products) 

• The Vulnerability:A massive RCE flaw thatdidn’t just affect firewalls—it impacted FortiVoice, FortiMail, FortiCamera, and FortiRecorder. 
• The 2025 Impact:This vulnerability highlighted the “IoT-ification” of enterprise security. Attackers pivoted from hardening firewalls to exploiting connected peripherals like security camera recorders (NVRs) and phone systems, which often share the same underlying OS code but receive less scrutiny.
• Why It Still Matters:Security teams often have blind spots for “appliance” hardware like VoIP controllers or NVRs. These devices sit on the same flat networks as critical servers but are patched far lessfrequently. They are currently acting as perfect, unmonitored jump-boxes for attackers. 

Palo Alto Networks PAN-OS: The Auth Bypass Chain 

CVE-2025-0108 & CVE-2025-4615 | Authentication Bypass 

• The Vulnerability:A pair of vulnerabilities that, when chained,allowed an unauthenticated attacker to bypass the management web interface login and execute commands with root privileges. 
• The 2025 Impact:This shattered the trust in the “management plane.” Attackers specifically targeted exposed management interfaces that were not locked down by ACLs. It forced a reckoning for organizations that had exposed theirfirewall admin portals to the open internet. 
• Why It Still Matters:Misconfiguration is the root cause here. Even patched firewallsremain vulnerable if their management interfaces are exposed. This vulnerability is a litmus test for your network segmentation strategy: if your admin portals are internet-facing, you are a target. 

Windows Kerberos: The Identity Crown Jewels 

CVE-2025-53779 | Privilege Escalation (Kerberos) 

• The Vulnerability:A flaw in the Kerberos authentication protocol allowing a user with low privileges to spoof tokens and elevate to Domain Admin active directory status.
• The 2025 Impact:Disclosedin the active “May 2025 Zero-Day Cluster,” this was a gift to ransomware operators. Once inside a network (perhaps via phishing), this vulnerability removed the need for complex lateral movement, providing an express elevator to Domain Admin rights. 
• Why It Still Matters:Patching Domain Controllers (DCs) is risky and requires careful orchestration. Consequently, many organizations lagbehind on DC updates. As long as this remains unpatched, any minor user compromise can instantly escalate into a catastrophic full-domain takeover. 

React / Next.js “React2Shell”: The Framework Implosion 

CVE-2025-55182 | Critical Unauthenticated RCE 

• The Vulnerability:A CVSS 10.0 vulnerability in the “Flight” protocol used by React 19 Server Components and Next.js (versions 15 and 16). It allows unauthenticated attackers to execute arbitrary code on the server simply by sending a crafted HTTP request that triggers unsafe deserialization.
• The 2025 Impact:Disclosedin early December, this became the single most critical application-layer event of the year. Within 24 hours of disclosure, threat intel firms observed massive scanning from China-nexus groups and botnets targeting millions of exposed Next.js applications. 
• Why It Still Matters:This is a “supply chain” crisis in your own code. Unlike a vendor appliance you can just “patch,” this requires rebuilding and redeploying your own web applications. Many organizationsdon’t even know they are running vulnerable versions of Next.js, as it is often embedded in third-party marketing sites, customer portals, and internal tools. 

Google Chrome (ANGLE): The Browser as the Endpoint 

CVE-2025-6558 | GPU Sandbox Escape 

• The Vulnerability:A flaw in the ANGLE graphics engine allowing attackers to escape the Chrome sandbox via a malicious website.
• The 2025 Impact:This was the definition of a “drive-by” compromise. Usersdidn’t need to download a file; they just had to visit a compromised site. It was heavily used in malvertising campaigns targeting corporate endpoints. 
• Why It Still Matters:The browser is the new OS. With hybrid work, the browser is the primary tool for accessing corporate data. An unpatched browser on a personal device accessing corporate SaaS is a direct tunnel into your data.

Apple ImageIO: The “Zero-Click” Ghost 

CVE-2025-43300 | Out-of-Bounds Write 

• The Vulnerability:A zero-day in Apple’sImageIO framework that processed malicious images, leading to code execution. 
• The 2025 Impact:Highly targeted. This was used in “zero-click” chains againstmobile devices of executives and high-value targets. 
• Why It Still Matters:Mobile devices are often the weak link in executive protection. This vulnerability reminds us that “secure by design” ecosystems like iOS are still susceptible to sophisticated, media-based attacks that require no user interaction.

Brocade Fabric OS: The Data Center Basement 

CVE-2025-1976 | Root Privilege Escalation 

• The Vulnerability:An IP validation flaw allowing local users to gain root accesson Fibre Channel switches. 
• The 2025 Impact:While less “noisy” than ransomware, this was critical for APTs establishing deep persistence in data center Storage Area Networks (SANs).
• Why It Still Matters:SAN switches are the “basement” of IT—installed and often forgotten. They are rarely scanned by vulnerability scanners and even more rarely patched. Compromise here means an attacker controls your storage data flow, potentially allowing for invisible data exfiltration or corruption.

Threats in Motion, Patches in Response: Insights from 2025 

The vulnerabilities above underscore a harsh reality: attackers are faster, smarter, and more automated than ever. Responding effectively requires not only awareness but speed—patching at the pace of threats. In 2025, organizations that stayed ahead of exploits leaned on robust patch management practices, turning raw vulnerability insights into actionable remediation. The following metrics, based on Action1’s aggregated and anonymized data, highlight how fast the patching landscape moved last year—and which applications drew the most attention from IT teams.  

2025 Patching Trends

• Patch Velocity: Increased by 58% compared to 2024, reflecting faster update cycles. 

• High-Urgency Updates: Critical patches rose by 30%, showing the continued pressure from urgent vulnerabilities. 

• Browser Updates: Browser-related patches grew 63% year-over-year, making browsers the most-patched category among third-party applications in 2025. 
• Top Patched Application families: Firefox family, Thunderbird ESR family , Office macOS family, Chrome family, Password managers 

These patching trends in 2025 continue patterns observed throughout the previous year, which were described in the Action1 2025 Software Vulnerability Ratings Report. Web browsers, which experienced the highest number of exploited vulnerabilities last year, remained the focus in 2025, receiving a high volume of patches and driving the fastest patch velocity. Similarly, the overall rise in critical vulnerabilities in 2024 set the stage for the surge in high-urgency updates observed this year. This illustrates that the 2025 patching landscape was shaped not only by immediate threats but also by ongoing, multi-year trends in vulnerability prevalence and exploit activity. 

If 2025 proved anything, it’s that vulnerabilities are no longer isolated events—they are part of an accelerated, interconnected threat landscape. From VPNs and firewalls to browsers and widely used applications, attackers exploited critical weaknesses faster than ever, making a strategic, risk-based approach to patch prioritization and remediation essential for organizations to stay ahead.