Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessObtain low-privilege local account
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DeliveryAuthenticate to vulnerable Windows system
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ExploitInvoke or monitor WinSock (afd.sys) data paths
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ExecutionCapture sensitive information transmitted in cleartext
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ImpactExfiltrate disclosed data
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A04:2025 - Cryptographic Failures
ASVS 5.0
V12 - Secure Communication Transport encryption
|
| Exploitation Conditions | Exploitation requires a locally authenticated session with at minimum a standard (low-privilege) user account on the affected Windows system - the CVSS vector PR:L confirms this. The attack is entirely local (AV:L); no network-based attack path exists. No user interaction by a third party is required once the attacker holds a local session. What limits exploitation: the attacker must first obtain local system access (physical, RDP, terminal services, etc.) through some means not covered by this CVE; remote unauthenticated exploitation is not possible. There is no indication from the description or SSVC data that any special non-default configuration is required - a standard Windows installation with the WinSock stack (present by default on all affected platforms) is sufficient. The limiting factor is purely the local access prerequisite, making this a post-compromise information disclosure risk rather than an initial-access vector. |
| Impact | The CVSS 3.1 score of 5.5 (Medium) accurately reflects a constrained local-only attack: AV:L eliminates remote exploitation, AC:L means no special circumstances are required once local access is obtained, and PR:L restricts exploitation to authenticated users - any domain or local account suffices. The C:H impact reflects that confidentiality exposure can be complete for the data in transit, but I:N and A:N mean no modification or disruption occurs. These CVSS signals align with SSVC findings: exploitation is classified as none, the attack is not automatable (no scripted remote path), and technical impact is partial. EPSS at 0.21% (11th percentile) further confirms that the security community has not observed or projected exploitation activity. The absence of KEV listing and no identified POC code reinforce low near-term risk. Real-world priority is accordingly low for network-perimeter defenses, but meaningful in environments where insider threats, shared workstations, multi-tenant VDI, or untrusted local users are threat model concerns. No conflicting signals between CVSS, EPSS, and SSVC were observed. |
| Exploit ScenarioDerived | An attacker who has obtained a low-privilege local account on a vulnerable Windows system - for example, through credential phishing or exploitation of a separate initial-access vulnerability - invokes Winsock API calls or monitors driver-level data paths to intercept sensitive information transmitted in cleartext through afd.sys. No public exploit code has been identified at time of analysis, meaning this scenario currently requires manual, targeted effort by a skilled local attacker rather than commodity tooling. |
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Alert meAnalysisAIv1 – Jul 22, 2026
Cleartext transmission of sensitive information in the Windows Ancillary Function Driver for WinSock (afd.sys) enables a locally authenticated, low-privilege attacker to intercept or read sensitive data that the driver handles without adequate protection. Affected platforms span Windows 10 (multiple versions), Windows 11, and Windows Server 2012 through 2025 as confirmed by EUVD version data and Microsoft CPE strings. No public exploit has been identified at time of analysis, EPSS is extremely low at 0.21% (11th percentile), and CISA SSVC classifies this as no active exploitation with non-automatable attack paths, positioning this as a low-urgency but meaningful local disclosure risk.
RemediationAI
Apply the vendor-released patch via Windows Update or the Microsoft Update Catalog; exact fixed build versions are defined per platform in the EUVD data (e.g., Windows 11 24H2 fixed at 10.0.26100.8875, Windows Server 2025 at 10.0.26100.33158, Windows Server 2022 at 10.0.20348.5386 - consult the full version table in the MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-34346). For systems where immediate patching is not feasible, restrict local interactive logon rights to the minimum required user set using Group Policy (User Rights Assignment: 'Allow log on locally' and 'Allow log on through Remote Desktop Services'), which raises the effective PR bar by limiting who can obtain local access in the first place. Additionally, enforcing application-layer TLS for sensitive communications handled by affected applications reduces the value of any data observable via this flaw - note this mitigates impact rather than the vulnerability itself. Windows Server 2012 and 2012 R2 are past end-of-life and should be prioritized for upgrade or enrolled in Extended Security Updates (ESU); continued reliance on compensating controls for these versions carries elevated long-term risk.
Affected VersionsENISA
Affected Packages
Source: OSV (Open Source Vulnerabilities)
Affects your stack
Affects 34 packages in microsoft, euvd
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Technical ContextAI · show details
The Windows Ancillary Function Driver for WinSock (afd.sys) is a kernel-mode driver that implements the core Winsock API layer, mediating socket creation, data transmission, and address resolution between user-space applications and the underlying transport stack. CWE-319 (Cleartext Transmission of Sensitive Information) indicates that sensitive data - potentially socket buffer contents, credentials, or application-layer payloads - is passed through this kernel component without encryption or adequate in-transit protection, making it observable to co-resident low-privilege processes. The local attack vector (AV:L) confirms exploitation is confined to the local machine context rather than being remotely triggerable. Affected product strings cover cpe:2.3:a:microsoft:windows_10_version_1607 through cpe:2.3:a:microsoft:windows_server_2012, indicating the flaw spans at least a decade of Windows releases.
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Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Local-only attack requiring a low-privilege authenticated session; confidentiality is high as sensitive data is fully exposed, but no integrity or availability impact applies.
Primary rating from Vendor (microsoft).
CVSS VectorVendor: microsoft
DescriptionCVE.org
Cleartext transmission of sensitive information in Windows Ancillary Function Driver for WinSock allows an authorized attacker to disclose information locally.
Threat Intelligence Overview
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.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.
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