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Windows UDFS CVE-2026-102215

| EUVDEUVD-2026-100368 HIGH
Heap-based Buffer Overflow (CWE-122)
2026-10-13 secure@microsoft.com GHSA-899r-9w6f-3jqh
7.8
CVSS 3.1 · Vendor: microsoft
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Obtain low-privileged local access
  2. Delivery
    Craft malformed UDF volume/image
  3. Exploit
    Induce UDFS driver to parse it
  4. Execution
    Trigger heap buffer overflow in kernel
  5. Impact
    Execute code as SYSTEM

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Heap buffer bounds checking
MITRE ATT&CK

1 technique across 1 tactic: Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires the attacker to already hold authenticated, low-privileged local code execution on the target (PR:L, AV:L) - this is a post-access privilege-escalation bug, not a remote entry point. The attacker must then cause the Windows UDFS (Universal Disk Format) file system driver to parse an attacker-controlled UDF volume, such as a malicious ISO, optical disc, or USB/removable image that is mounted or opened; the overflow is in the driver's parsing of that structure. Limiting factors: no remote network vector, no capability for a fully unauthenticated attacker, and the need to deliver and have the malformed UDF volume processed by the driver. No user interaction is required once the volume is presented (UI:N), and attack complexity is low (AC:L).

Impact

This is a credible operational priority but not an emergency. The provided CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H, base 7.8) describes a local privilege-escalation flaw: an attacker must already have the ability to execute code on the host as an authenticated low-privileged user (PR:L), after which low attack complexity (AC:L) and no user interaction (UI:N) make the exploit reliable, yielding full confidentiality, integrity and availability impact (C:H/I:H/A:H) - consistent with kernel-mode code execution via a vulnerable file system driver. No EPSS score was supplied, so exploitation probability cannot be quantified from this data. The CVE is NOT listed in CISA KEV and no public POC is referenced, so there is no public exploit identified at time of analysis. The signals are therefore internally consistent (all point to a serious-but-local EoP) rather than conflicting; the main caveat is that heap-overflow driver bugs are high-value second-stage exploits for sandbox escapes and post-compromise escalation, so despite the local-only vector it should be patched on Patch Tuesday cadence, prioritized on multi-user and endpoint systems where untrusted code or removable media (UDF/optical/ISO) is mounted.

Exploit ScenarioDerived

An attacker who already has low-privileged code execution on a Windows host (e.g., via phishing or a compromised standard user account) crafts a malformed UDF file system structure - for instance on a malicious ISO or optical/USB image - and triggers the Windows UDFS driver to parse it, overflowing a heap buffer. By grooming the kernel pool and corrupting adjacent structures, the attacker executes code in kernel context and elevates to SYSTEM. No public POC is referenced, and the low attack complexity (AC:L) means a working exploit would be reliable once developed.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
Patch available 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 13, 2026

Local privilege escalation in the Windows Universal Disk Format (UDFS) file system driver allows an authenticated, low-privileged attacker to corrupt kernel heap memory and elevate to SYSTEM by having the driver parse an attacker-controlled UDF volume. The defect is a heap-based buffer overflow (CWE-122) triggered when the driver processes a crafted UDF image - such as a malicious ISO, optical disc, or USB/removable media image - that is mounted or opened; no additional user interaction is required once the volume is presented (UI:N) and attack complexity is low (AC:L). Exploitation is not confirmed in the wild: no public exploit code and no CISA KEV listing were identified at time of analysis, and the CVSS 3.1 base score of 7.8 reflects the local, low-privilege prerequisite (AV:L/PR:L) combined with full confidentiality, integrity, and availability impact.

RemediationAI

Apply the Microsoft security update that addresses CVE-2026-102215 as documented in the MSRC Security Update Guide (https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-102215); no exact Knowledge Base or fix version was provided in the available data, so the advisory must be consulted to identify the correct patch for each affected Windows build, and standard monthly servicing should be prioritized on hosts that mount UDF media. Until patching completes, compensating controls include disabling automatic mounting of newly attached volumes so that a malicious UDF image is not parsed on insertion - for example by running "mountvol /N" or setting the automount registry value to 0 - with the trade-off that legitimate removable media must then be mounted manually by an administrator; disabling the UDFS driver entirely on systems that do not require ISO, optical, or UDF image support, at the cost of losing read access to UDF-formatted media; and restricting which low-privileged users can mount or format volumes and introducing untrusted removable media (for instance through device installation restrictions and removable-storage access policies), accepting the operational friction this places on legitimate media workflows. Because exploitation already requires authenticated local code execution, endpoint detection and privilege-escalation monitoring on processes that mount UDF volumes remains a useful secondary control, but patching is the only fix that removes the underlying heap overflow.

Affected VersionsENISA

Windows Server 2016 (Server Core installation) 10.0.14393.0 <10.0.14393.9612
Windows Server 2012 (Server Core installation) 6.2.9200.0 <6.2.9200.26434
Windows Server 2019 (Server Core installation) 10.0.17763.0 <10.0.17763.9376
Windows 10 Version 21H2 10.0.19044.0 <10.0.19044.7807
Windows Server 2012 6.2.9200.0 <6.2.9200.26434
Windows Server 2012 R2 (Server Core installation) 6.3.9600.0 <6.3.9600.23470
Windows 10 Version 1809 10.0.17763.0 <10.0.17763.9376
Windows Server 2012 R2 6.3.9600.0 <6.3.9600.23470
Windows 11 version 26H1 10.0.28000.0 <10.0.28000.3231
Windows Server 2022 10.0.20348.0 <10.0.20348.5761
Windows Server 2025 (Server Core installation) 10.0.26100.0 <10.0.26100.33650
Windows Server 2025 10.0.26100.0 <10.0.26100.33650
Windows 11 Version 24H2 10.0.26100.0 <10.0.26100.9711
Windows 11 Version 23H2 10.0.22631.0 <10.0.22631.7652
Windows 10 Version 22H2 10.0.19045.0 <10.0.19044.7807
Windows Server 2019 10.0.17763.0 <10.0.17763.9376
Windows Server 2016 10.0.14393.0 <10.0.14393.9612
Windows 10 Version 1607 10.0.14393.0 <10.0.14393.9612
Windows 11 Version 26H2 10.0.26300.0 <10.0.26300.9711
Windows 11 Version 25H2 10.0.26200.0 <10.0.26200.9711

Affected Packages

euvd windows_10_version_1607 fix: 10.0.14393.9612
euvd windows_10_version_1809 fix: 10.0.17763.9376
euvd windows_10_version_21h2 fix: 10.0.19044.7807
euvd windows_10_version_22h2 fix: 10.0.19044.7807
euvd windows_11_version_23h2 fix: 10.0.22631.7652
euvd windows_11_version_24h2 fix: 10.0.26100.9711
euvd windows_11_version_25h2 fix: 10.0.26200.9711
euvd windows_11_version_26h1 fix: 10.0.28000.3231
euvd windows_11_version_26h2 fix: 10.0.26300.9711
euvd windows_server_2012 fix: 6.2.9200.26434
euvd windows_server_2012_r2 fix: 6.3.9600.23470
euvd windows_server_2012_r2_server_core_installation fix: 6.3.9600.23470
euvd windows_server_2012_server_core_installation fix: 6.2.9200.26434
euvd windows_server_2016 fix: 10.0.14393.9612
euvd windows_server_2016_server_core_installation fix: 10.0.14393.9612
euvd windows_server_2019 fix: 10.0.17763.9376
euvd windows_server_2019_server_core_installation fix: 10.0.17763.9376
euvd windows_server_2022 fix: 10.0.20348.5761
euvd windows_server_2025 fix: 10.0.26100.33650
euvd windows_server_2025_server_core_installation fix: 10.0.26100.33650

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 20 packages in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

UDFS is the Windows kernel-mode file system driver that implements the ISO/IEC 13346 Universal Disk Format, the on-disk layout used by optical media (CD/DVD/Blu-ray), ISO images, and many removable or virtual disk images. Because the driver parses file-system metadata supplied by the volume itself - volume descriptors, partition maps, file entries, and allocation structures - an attacker who can supply a malformed volume controls data that reaches trusted kernel parsing code. This issue is a classic CWE-122 heap-based buffer overflow: a length or size field in a UDF structure is trusted without adequate bounds validation, so a copy into a heap allocation writes past its boundary and corrupts adjacent kernel pool memory. The vulnerability is not a remote network entry point; it is a post-access escalation primitive where an attacker who already holds authenticated low-privileged local code execution (PR:L, AV:L) must additionally deliver and cause the driver to process a crafted UDF volume. Successful heap corruption in kernel context can be shaped into controlled execution at SYSTEM integrity, which is what drives the C:H/I:H/A:H scoring. The authoritative fix and affected-build mapping are published by Microsoft in the MSRC Security Update Guide entry referenced below.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (microsoft) PRIMARY 7.8 HIGH
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 7.8 HIGH

Local driver bug requiring prior low-privileged code execution (AV:L, PR:L); reliable heap overflow with no user interaction (AC:L, UI:N) yields SYSTEM/kernel compromise (C:H/I:H/A:H).

3.1 AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.0 AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (microsoft).

CVSS VectorVendor: microsoft

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

2
Patch available
Oct 13, 2026 - 20:20 EUVD
CVE Published
Oct 13, 2026 - 19:17 nvd
HIGH 7.8

DescriptionCVE.org

Heap-based buffer overflow in Windows Universal Disk Format File System Driver (UDFS) allows an authorized attacker to elevate privileges locally.

Executive ViewAI

Why It Matters

Microsoft Windows systems are affected by a high-severity local privilege escalation flaw in the Universal Disk Format (UDFS) driver, which allows an authenticated low-privileged attacker to gain SYSTEM-level control by mounting a crafted UDF volume. This vulnerability poses a significant risk to organizational endpoints and servers that permit mounting of untrusted removable media, as successful exploitation could lead to complete compromise of affected machines. Leadership should prioritize mitigation because no patch is currently available and the flaw affects Windows systems that include the UDFS driver.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: disable the UDFS driver if not required; restrict the ability to mount untrusted UDF volumes via Group Policy or endpoint controls; enforce least privilege to limit low-privileged users from mounting crafted images; monitor for anomalous UDFS driver crashes or memory corruption events.

Threat Intelligence Overview

EPSS Score
0.3%
Top 77% exploitable
Prevalence
Ubiquitous
UDFS is a built-in driver shipped with all supported Windows versions
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation Less Likely
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.3%
Patch available Yes
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Defer
Exploitation
None
System Exposure· derived
Small
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

39
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +39
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

A heap overflow occurs when a program writes data beyond the bounds of a buffer allocated in the heap memory region.

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