CVE-2026-20683 in iOS
Summary
by MITRE • 09/14/2026
An authentication issue was addressed with improved state management. This issue is fixed in iOS 27 and iPadOS 27, macOS Golden Gate 27, macOS Sequoia 15.8, macOS Tahoe 26.7, visionOS 27. An app may be able to use the Sign In With Apple authentication flow to access the user's Apple Account.
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Analysis
by VulDB Data Team • 09/14/2026
The vulnerability described involves a flaw in the state management mechanisms within the Sign In with Apple authentication framework across multiple Apple operating systems including iOS iPadOS macOS and visionOS environments. This issue stems from improper handling of session states during the authentication process which can allow an application to bypass expected security controls or manipulate the flow to gain unauthorized access to user accounts. The core technical flaw lies in how the system validates and maintains the integrity of authentication tokens and state parameters when transitioning between different stages of the Sign In with Apple protocol. Specifically the failure to properly enforce strict validation checks on returned state values creates an opportunity for attackers to exploit inconsistencies that may lead to privilege escalation or account takeover scenarios where an app can impersonate a legitimate user without proper credentials.
From a technical perspective this vulnerability aligns closely with CWE-287 Improper Authentication as it represents a failure in the system's ability to correctly verify the identity of users during the authentication process. Additionally it relates to CWE-345 Insufficient Verification of Data Authenticity because the state management failures allow for potential manipulation of data that should be verified by the operating system before granting access. The operational impact is significant as Sign In with Apple is widely used across numerous applications providing a convenient single sign-on experience but also serving as a critical trust anchor for user identity verification. If exploited this flaw could enable malicious apps to hijack sessions or create unauthorized persistent logins thereby compromising user privacy and security while undermining the integrity of the authentication ecosystem that relies on these standardized flows.
This type of vulnerability is often associated with ATT&CK technique T1078 Valid Accounts where adversaries leverage legitimate credentials obtained through exploitation rather than brute force or phishing to maintain access within a system. By exploiting the state management flaw an attacker can effectively use valid but improperly managed authentication states to persist in compromised environments without triggering typical security alerts that monitor for anomalous login behaviors. The risk is further amplified by the widespread adoption of Sign In with Apple which means that successful exploitation could have broad implications affecting millions of users across different platforms and services integrated with this framework.
Mitigation strategies primarily involve applying the provided software updates to iOS iPadOS macOS and visionOS devices as these patches address the underlying state management deficiencies within the authentication libraries. Developers integrating Sign In with Apple should also ensure they are using the latest SDK versions which include enhanced validation logic for all returned parameters including nonce values and state identifiers. It is recommended that applications implement additional client-side checks to verify the consistency of session data before proceeding with sensitive operations even after system updates are applied as a defense-in-depth measure. Security teams should monitor logs for unusual patterns in authentication requests particularly those involving rapid succession or unexpected parameter variations which may indicate attempts to exploit this specific state management flaw until all systems are fully patched and validated against current security baselines.