CVE-2026-86898 in iOS
Summary
by MITRE • 09/15/2026
A logic issue was addressed with improved state management. This issue is fixed in Safari 27, iOS 27 and iPadOS 27, macOS Golden Gate 27, visionOS 27. Opening a maliciously crafted webarchive file may lead to universal cross-site scripting.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability described involves a critical logic error within the state management mechanisms of Apple's WebKit rendering engine, which powers Safari and other browser-based applications across its ecosystem including iOS, iPadOS, macOS, and visionOS. This flaw stems from an improper handling of internal states when processing specific types of web content, particularly those encapsulated in the .webarchive format. The core technical deficiency lies in how the application maintains context during the parsing and rendering phases, allowing a maliciously crafted file to manipulate these states in unintended ways. By exploiting this discrepancy between expected and actual state transitions, an attacker can inject executable scripts that bypass standard security boundaries designed to isolate web content from local system resources or other browsing contexts.
This specific flaw facilitates Universal Cross-Site Scripting, commonly referred as UXSS. Unlike traditional cross-site scripting which is constrained by the same-origin policy, a universal XSS vulnerability allows code injection into any website visited by the user, regardless of its domain origin. This occurs because the state management error compromises the isolation boundaries that WebKit enforces between different web contexts. When a user opens a malicious .webarchive file, the crafted content exploits the logic flaw to execute arbitrary JavaScript in the context of other open tabs or windows. This effectively neutralizes one of the most fundamental security models of modern browsers, enabling an attacker to read sensitive data from any site the user has authenticated with, such as banking portals, email services, or corporate intranets.
The operational impact of this vulnerability is severe due to its potential for widespread data exfiltration and session hijacking. An adversary can use this capability to steal cookies, local storage contents, and other persistent identifiers that maintain a user's logged-in state across various web applications. Furthermore, the attacker could perform actions on behalf of the victim by interacting with vulnerable interfaces in other tabs, such as transferring funds or changing account settings. The reliance on opening a .webarchive file suggests that this attack vector often requires some level of social engineering to trick the user into downloading and executing the malicious archive, although automated delivery mechanisms via compromised websites remain possible if they can trigger local file handling routines without explicit consent in certain configurations.
Mitigation strategies primarily involve immediate software updates provided by Apple. The issue has been resolved in Safari 27, iOS 27, iPadOS 27, macOS Golden Gate 27, and visionOS 27 through improved state management logic that ensures proper isolation of web content contexts during the parsing of complex archive files. Users should update their devices to these versions as soon as possible to patch this critical flaw. In addition to software updates, users are advised to exercise caution when opening .webarchive files from untrusted sources and to utilize browser security features such as Content Security Policy where applicable in development environments. From a defensive posture perspective, monitoring for unusual script execution patterns or unexpected cross-origin requests can help detect exploitation attempts in real-time before significant damage occurs.
This vulnerability aligns with CWE-94 Improper Control of Generation of Code (Code Injection) and specifically relates to the failure to maintain proper context isolation which is often categorized under CWE-1021 Improper Restriction of Rendered UI Layers or Frames. In terms of offensive security frameworks, this exploit maps directly to MITRE ATT&CK technique T1059 Command and Scripting Interpreter: JavaScript, utilized within the context of client-side attacks such as Client-Side Phishing (T1189) or Drive-by Compromise (T1189). The ability to bypass same-origin policies places this in a high-severity category requiring urgent remediation by administrators and end-users alike.