CVE-2026-43740: 
Apple Safari vulnerability analysis and mitigation

CVE-2026-43740 is a WebKit memory disclosure vulnerability affecting Apple Safari, iOS, iPadOS, and macOS Tahoe. The flaw stems from improper memory handling in the WebKit browser engine, where processing maliciously crafted web content may result in the disclosure of process memory. It was disclosed and patched on June 29, 2026, affecting all versions of Safari, iOS/iPadOS, and macOS Tahoe prior to 26.5.2. The vulnerability carries a CVSS v3.1 base score of 6.5 (Medium) (Apple iOS Advisory, Github Advisory).

The vulnerability is classified under CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) and CWE-416 (Use After Free), residing in the WebKit rendering engine (WebKit Bugzilla: 308046). Apple's advisory describes the root cause as a memory handling deficiency that was addressed with improved memory management. An unauthenticated remote attacker can exploit this by luring a victim to visit a maliciously crafted webpage; no privileges are required, but user interaction (visiting the page) is necessary. The fix was applied via additional restrictions on memory operations within WebKit, and the vulnerability was discovered by Nathaniel Oh (@calysteon) and Arni Hardarson (Apple iOS Advisory, Apple macOS Advisory).

Successful exploitation results in the disclosure of sensitive process memory from the Safari browser or the underlying operating system process, representing a high confidentiality impact with no integrity or availability impact. An attacker who tricks a user into visiting a malicious website could potentially extract in-memory data such as credentials, session tokens, or other sensitive information held in the browser process. The vulnerability affects a broad range of Apple devices including iPhone 11 and later, iPad Pro/Air/mini models, and macOS Tahoe systems (Apple iOS Advisory, Apple Safari Advisory).

1. Reconnaissance: Identify target users running unpatched versions of Safari, iOS/iPadOS, or macOS Tahoe prior to version 26.5.2 using social engineering or passive fingerprinting techniques.
2. Craft malicious web content: Develop a webpage containing specially crafted web content (e.g., JavaScript or HTML/CSS constructs) designed to trigger the improper memory handling flaw in WebKit's rendering engine.
3. Deliver the payload: Lure the victim to visit the malicious page via phishing email, malicious advertisement, or a compromised website. No authentication or special privileges are required on the attacker's side.
4. Trigger memory disclosure: When the victim's browser processes the crafted content, the WebKit vulnerability causes out-of-bounds or use-after-free memory access, leaking process memory contents back to the attacker-controlled page or server.
5. Exfiltrate data: Use JavaScript or network requests to transmit the disclosed memory contents (potentially containing credentials, tokens, or other sensitive data) to an attacker-controlled server (Apple iOS Advisory, Github Advisory).

• Network: Unusual outbound HTTP/HTTPS requests from Safari or WebKit-based browser processes to unknown or suspicious external domains shortly after visiting an unfamiliar website.
• Logs: Safari or system crash logs referencing WebKit memory access violations or unexpected memory reads; entries in /Library/Logs/DiagnosticReports/ or ~/Library/Logs/DiagnosticReports/ related to Safari or WebContent process crashes.
• Process: Unexpected WebContent process (com.apple.WebKit.WebContent) spawning network connections or exhibiting abnormal memory usage patterns.
• File System: Unexpected files written by the Safari or WebContent process in temporary directories, potentially indicating follow-on payload staging.

Apple has released patches addressing this vulnerability in Safari 26.5.2, iOS 26.5.2 and iPadOS 26.5.2, and macOS Tahoe 26.5.2, all released on June 29, 2026. Users should update their devices immediately via Settings > General > Software Update (iOS/iPadOS) or System Settings > General > Software Update (macOS). As a temporary workaround for high-risk users unable to patch immediately, avoiding untrusted or unfamiliar websites and considering disabling JavaScript in Safari settings can reduce exposure (Apple iOS Advisory, Apple macOS Advisory, Apple Safari Advisory).

The June 29, 2026 Apple security update received coverage from technology media outlets including Lifehacker, which highlighted the broader batch of security fixes and urged users to update their iPhones promptly. The SANS Internet Storm Center published a diary entry (ISC Diary 33114) summarizing the update. The Zero Day Initiative (ZDI) published a June 2026 Apple Security Update Review covering the release. The update was also noted in the WebKitGTK security advisory ecosystem, with Fedora issuing related WebKitGTK package updates shortly after.