CVE-2026-78628 in Credential Provider for Windows
Summary
by MITRE • 10/15/2026
The Okta Credential Provider for Windows does not validate a serialized credential buffer before interpreting it as a Kerberos logon structure. The buffer size and packed string offsets are not checked. Processing a malformed buffer can cause the credential provider process to terminate unexpectedly or lead to out-of-bounds memory reads and writes, which may result in the disclosure of adjacent process memory into local system logs.
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Analysis
by VulDB Data Team • 10/15/2026
The Okta Credential Provider for Windows contains a critical input validation flaw within its Kerberos logon processing logic that allows attackers to exploit improper handling of serialized credential buffers. This vulnerability stems from the application's failure to perform rigorous boundary checks on buffer sizes and string offsets before interpreting the data as a valid Kerberos authentication structure. In standard security architecture, any external or semi-trusted input stream must be validated against expected constraints prior to parsing; however, in this instance, the provider proceeds directly with deserialization without verifying that the reported length of the buffer matches its actual allocated size or that string offsets remain within safe memory boundaries. This lack of validation creates a direct pathway for attackers to craft maliciously formatted authentication requests that bypass normal security controls during the Windows logon sequence.
The technical impact of this flaw is severe, manifesting as both denial-of-service conditions and potential information disclosure vulnerabilities. When a malformed buffer is processed, the application may attempt to access memory locations outside the allocated heap or stack space, leading to out-of-bounds reads and writes. These memory corruption errors typically cause the credential provider process to crash unexpectedly, resulting in a denial of service for users attempting to authenticate through Okta on affected Windows systems. More critically, if an attacker can control the content written via these out-of-bounds operations or manipulate read pointers, they may trigger information leaks where adjacent process memory is exposed into local system logs. This could potentially reveal sensitive data such as cryptographic keys, session tokens, or other privileged credentials stored in the surrounding memory space of the authentication service.
From a threat modeling perspective, this vulnerability aligns with CWE-120 Buffer Copy without Checking Size of Input and CWE-787 Out-of-bounds Write, reflecting fundamental errors in secure coding practices regarding memory management. The exploitation vector falls under MITRE ATT&CK technique T1556, specifically related to modifying authentication processes or credential providers, as the attacker interacts directly with the Windows logon subsystem. By compromising the integrity of the credential provider, an adversary could potentially intercept or manipulate authentication flows, although the primary confirmed impact in this specific instance is memory corruption and data leakage rather than direct privilege escalation through code execution. The severity is heightened by the fact that credential providers operate at a high level of trust within the Windows operating system architecture, often running with elevated privileges to facilitate seamless single sign-on experiences across enterprise environments.
Mitigation strategies must prioritize immediate patching using vendor-provided updates that enforce strict input validation and bounds checking on all serialized data structures before interpretation. Security teams should also implement network segmentation and application whitelisting to restrict the execution of untrusted code within systems running vulnerable versions of the Okta Credential Provider. Additionally, monitoring for anomalous process terminations or unusual memory access patterns in Windows event logs can help detect exploitation attempts in real time. Organizations relying on this integration should verify their current version against known affected releases and apply security patches as soon as they become available to close the gap that allows malformed buffers to trigger these critical memory safety violations.