CVE-2026-43740 Overview
CVE-2026-43740 is a memory handling vulnerability affecting Apple Safari, iOS, iPadOS, and macOS. Processing maliciously crafted web content may result in the disclosure of process memory. The flaw is categorized under [CWE-119] (improper restriction of operations within the bounds of a memory buffer). Apple addressed the issue in Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, and macOS Tahoe 26.5.2 through improved memory handling. Attackers can exploit the vulnerability remotely by luring victims to malicious web pages, requiring user interaction but no privileges.
Critical Impact
Attackers can extract sensitive data from Safari process memory by tricking users into visiting crafted web content, potentially exposing credentials, session tokens, or other in-process secrets.
Affected Products
- Apple Safari (versions prior to 26.5.2)
- Apple iOS and iPadOS (versions prior to 26.5.2)
- Apple macOS Tahoe (versions prior to 26.5.2)
Discovery Timeline
- 2026-06-29 - CVE-2026-43740 published to NVD
- 2026-06-30 - Last updated in NVD database
Technical Details for CVE-2026-43740
Vulnerability Analysis
The vulnerability resides in Apple's web content processing stack, most likely within WebKit's rendering or JavaScript execution paths. When Safari parses maliciously crafted web content, improper memory handling allows adjacent process memory to be read outside of intended boundaries. This class of flaw commonly leads to information disclosure of pointers, heap contents, or cached credentials residing in the renderer process.
The issue is classified as [CWE-119], indicating a boundary violation during buffer operations. The Exploit Prediction Scoring System (EPSS) currently rates this vulnerability at 0.203% probability of exploitation, placing it in the 10th percentile.
Root Cause
Apple's advisory states the fix involved "improved memory handling," indicating the original code path failed to correctly validate buffer bounds or object lifetimes when parsing attacker-controlled input. Such flaws typically arise from missing size checks, incorrect pointer arithmetic, or improper initialization of memory buffers before use. The result is that portions of process memory outside the intended data structure become accessible to attacker-supplied scripts.
Attack Vector
Exploitation requires an attacker to host or inject malicious web content and convince a victim to load it in a vulnerable Safari version. Once the crafted page is rendered, the malformed content triggers the memory handling flaw, allowing JavaScript or other content to observe leaked memory contents. The attack works over the network with low complexity and no authentication, but requires user interaction. No public proof-of-concept or in-the-wild exploitation has been reported. Refer to the Apple Support Document #127594 for vendor technical details.
Detection Methods for CVE-2026-43740
Indicators of Compromise
- Safari or WebKit-based application crashes correlated with visits to untrusted domains, particularly renderer process termination reports.
- Outbound connections from browser processes to newly observed domains hosting obfuscated JavaScript payloads.
- Anomalous data exfiltration patterns following user visits to unfamiliar web pages on unpatched Apple devices.
Detection Strategies
- Inventory Apple endpoints and identify systems running Safari, iOS, iPadOS, or macOS versions below 26.5.2.
- Monitor crash telemetry from com.apple.WebKit.WebContent and related renderer processes for repeated faults tied to specific URLs.
- Correlate browser process behavior with network telemetry to identify potential exploitation attempts against unpatched hosts.
Monitoring Recommendations
- Enable centralized logging of browser crash reports and unified log entries referencing WebKit memory faults.
- Track DNS and HTTP telemetry for connections to suspicious domains delivered through phishing or malvertising channels.
- Alert on outdated Safari, iOS, iPadOS, or macOS builds detected across managed device inventories.
How to Mitigate CVE-2026-43740
Immediate Actions Required
- Update all Apple devices to Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, or macOS Tahoe 26.5.2 as applicable.
- Prioritize patching for users who routinely browse untrusted content or handle sensitive data in the browser.
- Communicate phishing awareness guidance to users, emphasizing risks from unsolicited links and web content.
Patch Information
Apple has released fixes in Safari 26.5.2, iOS 26.5.2, iPadOS 26.5.2, and macOS Tahoe 26.5.2. Details are available in Apple Support Document #127594, Apple Support Document #127595, and Apple Support Document #127685. Deploy the updates through Mobile Device Management (MDM) tooling or macOS Software Update mechanisms.
Workarounds
- Restrict use of Safari on unpatched systems and route users to a patched alternative browser where feasible.
- Enforce network-level filtering to block known malicious domains and reduce exposure to crafted web content.
- Enable content security policies and script-blocking extensions on high-risk endpoints until patches are deployed.
# Verify installed Safari version on macOS
mdls -name kMDItemVersion /Applications/Safari.app
# Trigger macOS software update check
sudo softwareupdate --list
sudo softwareupdate --install --all --restart
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
