CVE-2026-43667 Overview
CVE-2026-43667 is a reachable assertion vulnerability [CWE-617] affecting Apple iOS and iPadOS. An attacker in a privileged network position can trigger the assertion and cause a denial-of-service condition on the target device. Apple addressed the issue with improved input validation in iOS 18.7.10 and iPadOS 18.7.10. Exploitation requires user interaction, and the flaw does not compromise confidentiality or integrity. The vulnerability is tracked in the Apple Support Document.
Critical Impact
A network-adjacent attacker can force affected iOS and iPadOS devices into a denial-of-service state, disrupting device availability.
Affected Products
- Apple iOS (versions prior to 18.7.10)
- Apple iPadOS (versions prior to 18.7.10)
- Devices supported by the iOS/iPadOS 18.7.x update train
Discovery Timeline
- 2026-08-17 - CVE-2026-43667 published to the National Vulnerability Database (NVD)
- 2026-08-18 - Last updated in NVD database
Technical Details for CVE-2026-43667
Vulnerability Analysis
The flaw is a reachable assertion classified under [CWE-617]. Reachable assertions occur when attacker-controlled input drives program state into a condition that fails an internal assert() check. When the assertion fires, the process terminates abnormally, resulting in a denial-of-service. Apple's advisory states the fix uses improved input validation to reject the malformed inputs before they reach the assertion. The impact is limited to availability; the vulnerability does not enable code execution, data disclosure, or privilege escalation.
Root Cause
The root cause is insufficient validation of network-supplied data before it reaches an internal consistency check. When unexpected values propagate to a runtime assertion, the assertion evaluates false and terminates the affected component. Apple's remediation adds input validation prior to the assertion, ensuring malformed data is rejected rather than allowed to trigger the abort.
Attack Vector
Exploitation requires an attacker in a privileged network position, such as an on-path adversary controlling a Wi-Fi network, a proxy, or an upstream router. The attacker crafts malformed network traffic that reaches the vulnerable component on the target device. User interaction is required, indicating that the victim must initiate a network action such as opening a resource or connecting to a service. Successful exploitation crashes the affected process and produces a denial-of-service condition.
No public proof-of-concept or exploit code is available at the time of publication, and the vulnerability is not listed on the CISA Known Exploited Vulnerabilities catalog. See the Apple security advisory for vendor-supplied technical detail.
Detection Methods for CVE-2026-43667
Indicators of Compromise
- Unexpected process termination or system reboot events on iOS or iPadOS devices following network activity on untrusted networks
- Repeated application crashes correlated with connections to attacker-controlled Wi-Fi access points or proxies
- Crash logs on the device referencing assertion failures in networking components
Detection Strategies
- Collect and review iOS and iPadOS crash reports through mobile device management (MDM) telemetry for assertion-failure signatures
- Monitor enterprise Wi-Fi and VPN logs for malformed protocol traffic targeting mobile clients
- Correlate device crash events with network position anomalies, such as rogue access points or unexpected captive portals
Monitoring Recommendations
- Enforce MDM policies that report device OS version and flag devices running iOS or iPadOS below 18.7.10
- Alert on repeated mobile device disconnects or reboots on the same network segment, which may indicate active exploitation attempts
- Track network-layer anomalies at enterprise Wi-Fi controllers to identify on-path attacker behavior
How to Mitigate CVE-2026-43667
Immediate Actions Required
- Update all iPhone and iPad devices to iOS 18.7.10 or iPadOS 18.7.10 through Settings > General > Software Update
- Use MDM to push the update to managed devices and enforce compliance deadlines
- Advise users to avoid untrusted Wi-Fi networks until patching is complete
Patch Information
Apple released iOS 18.7.10 and iPadOS 18.7.10 to fix CVE-2026-43667 by adding improved input validation. Refer to the Apple Support Document for the full advisory and applicable device models.
Workarounds
- Restrict device use to trusted networks such as corporate Wi-Fi with WPA3 and certificate-based authentication
- Require always-on VPN through MDM to reduce exposure to on-path attackers on public networks
- Disable auto-join for open Wi-Fi networks to prevent unintended association with attacker-controlled access points
# Example MDM compliance rule (pseudocode)
# Require iOS/iPadOS >= 18.7.10
compliance_policy:
platform: iOS
minimum_os_version: "18.7.10"
action_on_noncompliance: block_corporate_access
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
