Microsoft’s Patch Tuesday releases in 2025 tell a clear and sobering story: record-breaking vulnerability volume, sustained zero-day exploitation, and a decisive attacker shift toward privilege escalation and identity abuse. When viewed as a visual timeline, the year reveals not just patch counts, but attacker intent.
This blog explains every major element of the 2025 Patch Tuesday timeline, month by month, and highlights the single most critical vulnerability from each release, based on severity, exploitability, and real-world impact.
The Big Picture: What 2025 Looked Like at a Glance
Across the year, Microsoft patched:
- 1,130+ vulnerabilities
- 41 zero-day flaws
- 24 vulnerabilities actively exploited in the wild
These numbers place 2025 among the most aggressive Patch Tuesday years in Microsoft’s history. More importantly, many patches were reactive, addressing vulnerabilities already abused by attackers—underscoring the shrinking window between exploitation and remediation.
Month-by-Month Timeline with Critical CVEs
January 2025 — Virtualization Boundaries Broken
- 157 CVEs
- 10 Critical
Most Critical CVE: CVE-2025-21333
Hyper-V Elevation of Privilege
January opened with one of the largest Patch Tuesdays of the year. The standout vulnerability allowed a guest virtual machine to escalate privileges on the host, effectively crossing a trust boundary.
Why it mattered:
Hyper-V underpins enterprise virtualization and cloud workloads. A host escape dramatically expands the blast radius of any compromise, especially in multi-tenant environments.
February 2025 — Quiet Month, Dangerous Flaws
- 55 CVEs
- 2 Zero-Days
Most Critical CVE: CVE-2025-21412
Windows Kernel Elevation of Privilege
February’s lower volume masked its danger. Kernel-level privilege escalation flaws dominated, enabling attackers to convert initial access into full SYSTEM control.
Why it mattered:
EoP vulnerabilities are ideal second-stage exploits, heavily favored by ransomware operators and post-exploitation frameworks.
March 2025 — Kernel Zero-Days in the Wild
- 56 CVEs
- 6 Critical
Most Critical CVE: CVE-2025-24983
Win32 Kernel Subsystem EoP – Actively Exploited
March marked a turning point with confirmed in-the-wild exploitation of a kernel zero-day.
Why it mattered:
Kernel zero-days bypass most endpoint defenses. Organizations that delayed patching faced immediate compromise risk.
April 2025 — Network Services Under Attack
- 121 CVEs
- 11 Critical
Most Critical CVE: CVE-2025-21204
Windows LDAP Remote Code Execution
April highlighted network-facing services, particularly LDAP.
Why it mattered:
LDAP sits at the heart of Active Directory. RCE vulnerabilities here threaten domain-wide compromise, often without valid credentials.
May 2025 — Drivers as Weapons
- 121 CVEs
- Multiple Zero-Days
Most Critical CVE: CVE-2025-26644
Windows Kernel Driver Elevation of Privilege
Attackers abused trusted drivers to escalate privileges and disable security controls.
Why it mattered:
Driver exploitation is a common technique to blind EDR solutions, making this month especially relevant to ransomware defense.
June 2025 — Legacy Protocols Strike Back
- 66+ CVEs
- 9 Critical
Most Critical CVE: CVE-2025-33073
WebDAV Remote Code Execution
A critical RCE in WebDAV reminded defenders that legacy components remain exploitable.
Why it mattered:
WebDAV is often forgotten but widely enabled, enabling unauthenticated remote compromise.
July 2025 — Core OS Exposure
- 130+ CVEs
- Double-Digit Critical
Most Critical CVE: CVE-2025-38112
Windows Graphics Component RCE
This flaw could be triggered through malicious content rendering.
Why it mattered:
Graphics subsystem vulnerabilities are low-interaction and commonly used for phishing-based initial access.
August 2025 — Identity Becomes the Battlefield
- 130+ CVEs
- 14 Critical
Most Critical CVE: CVE-2025-53779
Kerberos Elevation of Privilege – Zero-Day
August was dominated by authentication flaws, with Kerberos at the center.
Why it mattered:
Kerberos exploitation enables lateral movement, persistence, and domain escalation, making it one of the most strategically dangerous flaws of the year.
September 2025 — Trust Infrastructure Weaponized
- 167 CVEs
- 17 Critical (Highest in 2025)
Most Critical CVE: CVE-2025-59287
WSUS Remote Code Execution
This vulnerability allowed attackers to exploit Windows Server Update Services.
Why it mattered:
WSUS is implicitly trusted. Exploitation enables internal supply-chain attacks, turning update infrastructure into a delivery mechanism.
October 2025 — Record Volume, Server Risk
- 167+ CVEs
- Multiple Critical RCEs
Most Critical CVE: CVE-2025-59230
Windows Server Remote Code Execution
October delivered the highest patch volume of the year, with server-side RCEs standing out.
Why it mattered:
Server RCE vulnerabilities enable direct compromise of enterprise infrastructure and cloud workloads.
November 2025 — Patch Fatigue Exploited
- 63 CVEs
- 4 Critical
Most Critical CVE: CVE-2025-62215
Windows Kernel EoP – Actively Exploited
Attackers took advantage of year-end patch fatigue with an actively exploited kernel flaw.
Why it mattered:
Late-year exploitation often succeeds because patch cycles slow down—attackers know this.
December 2025 — Cloud Integration Risks
- 56 CVEs
- 3 Critical
Most Critical CVE: CVE-2025-62221
Cloud Files Mini Filter Driver EoP – Zero-Day
The year closed with zero-days affecting cloud file synchronization.
Why it mattered:
Hybrid and cloud-integrated components are now first-class attack surfaces, not edge cases.
Strategic Themes from the Timeline
Zero-Days Are Now Routine
Zero-day exploitation occurred throughout the year, reinforcing that patching is often containment, not prevention.
Privilege Escalation Dominates
Elevation of Privilege was the most common impact category, reflecting attacker focus on post-compromise control.
Trust Boundaries Are the Target
Kerberos, Hyper-V, WSUS, and kernel drivers all represent implicit trust zones—and attackers are actively dismantling them.
Impact Category Breakdown
Microsoft classifies CVEs into seven impact categories:
- Elevation of Privilege (EoP)
- Remote Code Execution (RCE)
- Information Disclosure
- Denial of Service (DoS)
- Spoofing
- Security Feature Bypass
- Tampering
What Each Category Means
Elevation of Privilege (EoP) — ~433 CVEs (38.3%)
- Most prevalent attack type in 2025.
- These flaws allow an attacker (often after initial access) to escalate their privileges on a host — from a limited user to SYSTEM or NETWORK SERVICE.
- Commonly leveraged in ransomware and post-compromise attack chains.
Trend: EoP overtook RCE as the dominant impact in 2025.
Remote Code Execution (RCE) — ~348 CVEs (30.8%)
- Second most frequent category.
- Enables attackers to run arbitrary code on a target system, often without prior authentication.
- Includes network-facing and user interaction flaws. Why it matters: RCE is often the initial foothold in an attack.
Information Disclosure — ~160 CVEs (14.2%)
- These allow attackers to access sensitive information (memory, files, credentials) they normally shouldn’t see.
- Can facilitate reconnaissance and enable other attack phases.
Denial of Service (DoS) — ~87 CVEs (7.7%)
- Flaws that let attackers crash or hang services.
- Not usually direct compromise vectors but can be combined with other techniques to disrupt defenses.
Security Feature Bypass — ~28 CVEs (2.5% estimated)
- Vulnerabilities that circumvent security controls, such as bypassing sandboxing or protection mechanisms.
- Not always high volume, but often critical for complex chains.
Spoofing — ~28 CVEs (2.5% estimated)
- Enables attackers to pretend to be another component, user, or process.
- Often a supporting weakness in more complex attacks.
Tampering — ~4 CVEs (0.4%)
- Least common category in 2025.
- These flaws involve unauthorized modification of data or code paths.
- Rare but still represents integrity risks.
Insight: Why These Splits Matter
1. EoP’s High Prevalence — Threat Focus Shift
In 2025, EoP vulnerabilities represented the largest proportion of patched CVEs (38.3%), suggesting attackers and defenders alike are focused on post-compromise control. This differs from earlier years, when RCE was often dominant.
Security implication: Patch management alone isn’t enough — strong identity/access controls and privilege segmentation are critical.
2. RCE Still a Major Entry Vector
Although second in count, RCE vulnerabilities remain one of the most dangerous attack categories. Successful RCE often leads to unauthorized access, malware deployment, and full system compromise.
Security implication: Network filters, application whitelisting, and exploit mitigation technologies remain high priority.
3. Information Disclosure and DoS — Supporting but Significant
Even though not dominant, these categories play secondary roles in multi-stage exploits.
- Information disclosure can leak secrets used for credential theft.
- DoS can distract defenders or aid in denial of incident response capabilities.
4. Smaller Categories Are Still Relevant
While security feature bypass and spoofing account for smaller portions of the yearly total, these flaws often enable or amplify RCE/EoP attacks (e.g., bypassing protections to enable execution of malicious code).
Summary Table
| Impact Category | Approx. Count | % of Total CVEs |
|---|---|---|
| Elevation of Privilege (EoP) | ~433 | 38.3% |
| Remote Code Execution (RCE) | ~348 | 30.8% |
| Information Disclosure | ~160 | 14.2% |
| Denial of Service (DoS) | ~87 | 7.7% |
| Security Feature Bypass | ~28 | ~2.5% |
| Spoofing | ~28 | ~2.5% |
| Tampering | ~4 | 0.4% |
| Total | ~1,130 | 100% |
Note: Microsoft’s official totals do not always publish exact counts for spoofing and bypass categories, but percentages for major categories (EoP, RCE, Info Disclosure, DoS, Tampering) are explicitly documented. The smaller categories (spoofing, security feature bypass) are inferred based on the remainder after major categories are summed.
Final Takeaway
Microsoft Patch Tuesday 2025 was not about fixing bugs—it was about defending trust.
Attackers consistently targeted:
- Kernel and driver layers
- Identity and authentication services
- Trusted infrastructure components
For defenders, the lesson is clear:
Patch fast, prioritize zero-days and EoP flaws, and assume attackers already have initial access.
