CVE-2026-42969: Windows Push Notifications Information Disclosure Vulnerability

Technical summary

The vulnerability stems from use of an uninitialized resource (CWE-908) within the Windows Push Notifications architecture. When the Push Notifications service initializes certain memory structures, it fails to properly zero or validate the contents before use. An authenticated local attacker can craft requests or conditions that cause the service to expose uninitialized memory contents, potentially revealing cached credentials, encryption keys, or other sensitive information residing in that memory region. The flaw does not permit code execution or service disruption—only information disclosure.

Business impact

For enterprise environments, this vulnerability introduces a lateral movement and privilege escalation risk. A user with standard permissions on a Windows machine could extract sensitive data from memory that might include credentials for elevated accounts, API tokens, or other secrets used by system services. In multi-user or shared-device scenarios (common in call centers, labs, and shared workspaces), compromised credentials could grant attackers access to corporate resources or cloud services. The impact is amplified in environments where Windows 10 and 11 systems hold PII, intellectual property, or authentication material.

Affected systems

The vulnerability affects a broad range of Microsoft Windows platforms: Windows 10 (versions 1607, 1809, 21H2, and 22H2), Windows 11 (versions 23H2, 24H2, 25H2, and 26H1), and Windows Server editions 2016, 2019, 2022, and 2025. This spans both client and server operating systems, meaning both desktop workstations and infrastructure may require patching. Organizations running Windows 10 long-term servicing branches should treat this as a priority given the widespread use of these versions.

Exploitability

Exploitability is limited by the requirement for local authenticated access; the attacker must already have valid credentials or a user session on the affected machine. No network component exists, no user interaction is needed beyond local presence, and the attack is straightforward once access is established. This reduces external threat likelihood but elevates insider and post-compromise risk. The CVSS 3.1 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N) reflects this: local attack vector, low complexity, low privilege requirement, and high confidentiality impact. The vulnerability is not currently tracked in the KEV catalog, suggesting no evidence of active exploitation in the wild at this time.

Remediation

Microsoft will address this issue through security updates distributed via Windows Update. Organizations should apply patches as they become available through standard servicing channels. For Windows 10, patches will be delivered to supported versions; for Windows 11, all supported releases will receive updates. Windows Server administrators should prioritize systems handling sensitive workloads or serving as credential stores. Test patches in a staging environment before broad deployment to ensure compatibility with line-of-business applications.

Patch guidance

Monitor Microsoft's security update releases and apply patches to all affected Windows versions listed above. Verify patch deployment through Windows Update or WSUS management tools. For Server environments, coordinate patching to minimize disruption; out-of-band updates may be issued if severity increases. Check Microsoft's official security advisory for specific KB article numbers and version mappings, as these are not yet finalized in public guidance. Prioritize machines with high-value user accounts or those running services that handle secrets and credentials.

Detection guidance

Detection of active exploitation is challenging because the vulnerability manifests as local memory access rather than network traffic or obvious file system changes. Monitor Windows Push Notification service logs and Event Viewer for unusual activity—crashes, restarts, or unexpected privilege changes. Use endpoint detection and response (EDR) tools to flag processes attempting to interact with Push Notification service memory regions or making unexpected system calls. Monitor for suspicious credential usage patterns post-compromise (e.g., credentials used from unexpected locations or times). Behavioral analytics may flag privilege escalation attempts following information disclosure.

Why prioritize this

Although the CVSS score of 5.5 is medium, this vulnerability should be prioritized in environments where local user access is a realistic threat vector: shared devices, developer workstations, or systems accessed by contractors. The high confidentiality impact and broad affected product list make this a concern for any organization running Windows 10 or 11 at scale. Lack of KEV designation suggests no imminent active exploitation, but the information disclosure nature makes it attractive for targeted attacks seeking credentials. Organizations with stringent data protection requirements should treat this as high-priority.

Risk score, explained

The CVSS 3.1 score of 5.5 reflects a medium-severity vulnerability with high confidentiality impact but requiring local authenticated access. The score appropriately penalizes the local-only attack vector and privilege requirement, but rewards the high likelihood of sensitive data exposure. For security teams, the score should not be interpreted as low risk; rather, it reflects a realistic but not catastrophic threat. Organizations with robust access controls and secrets management may accept a longer patching window, while those with weaker insider-threat controls should expedite remediation.

Frequently asked questions