CVE-2026-43813 Overview
CVE-2026-43813 is an input validation vulnerability [CWE-20] affecting multiple Apple operating systems. A maliciously crafted application can bypass code signing enforcement on affected devices. Apple resolved the issue through improved input sanitization across its platform releases.
The flaw requires local access and user interaction, but successful exploitation compromises confidentiality and integrity by allowing unsigned or tampered code to execute under trusted contexts. Apple addressed the issue in iOS 26.6, iPadOS 26.6, macOS Tahoe 26.6, tvOS 26.6, visionOS 26.6, and watchOS 26.6.
Critical Impact
A malicious app can circumvent Apple's code signing enforcement, undermining a foundational trust boundary used to prevent execution of unauthorized code.
Affected Products
- Apple iOS and iPadOS (versions prior to 26.6)
- Apple macOS Tahoe (versions prior to 26.6)
- Apple tvOS, visionOS, and watchOS (versions prior to 26.6)
Discovery Timeline
- 2026-07-27 - CVE-2026-43813 published to NVD
- 2026-07-28 - Last updated in NVD database
Technical Details for CVE-2026-43813
Vulnerability Analysis
CVE-2026-43813 is an improper input validation flaw [CWE-20] in the code signing enforcement path of Apple operating systems. Code signing on Apple platforms verifies that executable code originates from a trusted developer and has not been altered after signing. When enforcement can be bypassed, attackers gain the ability to run code that would normally be rejected by the kernel or runtime loader.
Apple's advisory states the issue was addressed with improved input sanitization, indicating that specifically crafted inputs to a validation routine caused the enforcement logic to accept content it should have rejected. The vulnerability affects the shared code signing infrastructure common to iOS, iPadOS, macOS, tvOS, visionOS, and watchOS.
Root Cause
The root cause is insufficient sanitization of input processed during code signature validation. Malformed or crafted structures within an application bundle can lead the enforcement mechanism into a state where signature checks are effectively bypassed. Apple's fix hardens input handling within this validation path.
Attack Vector
Exploitation requires an attacker to deliver a maliciously crafted application to the target device and convince the user to run it. Once executed locally, the app leverages the validation flaw to bypass code signing enforcement, enabling execution of code that would ordinarily be blocked. Because the vulnerability is local and requires user interaction, mass exploitation over the network is not the primary risk model; targeted delivery via sideloading, social engineering, or supply chain compromise is more plausible.
No public proof-of-concept exploit is currently associated with this CVE, and it is not listed in the CISA Known Exploited Vulnerabilities catalog. The EPSS probability is 0.129%, reflecting low predicted exploitation activity at time of publication.
Detection Methods for CVE-2026-43813
Indicators of Compromise
- Unexpected applications running with entitlements or capabilities not consistent with their declared signature.
- Application bundles with malformed or inconsistent code signing metadata inside _CodeSignature directories.
- Processes spawned from user-writable locations executing binaries whose signatures fail out-of-band validation.
Detection Strategies
- Perform out-of-band signature verification using codesign --verify --deep --strict on macOS to identify binaries whose signature state differs from what the OS reports.
- Monitor for installation of applications from non-App Store sources on managed devices via MDM inventory reporting.
- Correlate execution telemetry with expected code signing identifiers, flagging executions whose team identifiers do not match the declared publisher.
Monitoring Recommendations
- Enable and forward endpoint telemetry from Apple devices (process execution, file writes to application bundles) to a centralized analytics platform.
- Track OS version compliance across the fleet and alert on devices remaining below the 26.6 baseline.
- Baseline the set of signed applications running in the environment and alert on new bundle identifiers or unusual entitlements.
How to Mitigate CVE-2026-43813
Immediate Actions Required
- Update all Apple devices to iOS 26.6, iPadOS 26.6, macOS Tahoe 26.6, tvOS 26.6, visionOS 26.6, or watchOS 26.6.
- Enforce OS version minimums through mobile device management (MDM) policies and block non-compliant devices from sensitive resources.
- Restrict installation of applications to trusted sources such as the App Store or an MDM-managed catalog.
- Review recently installed applications on managed endpoints for unexpected publishers or bundles.
Patch Information
Apple released patches in iOS 26.6, iPadOS 26.6, macOS Tahoe 26.6, tvOS 26.6, visionOS 26.6, and watchOS 26.6. Full details are available in the Apple Security Advisory #128066, Apple Security Advisory #128067, Apple Security Advisory #128068, Apple Security Advisory #128069, and Apple Security Advisory #128070.
Workarounds
- No vendor-supplied workaround exists; patching is the definitive mitigation.
- Limit user ability to install applications outside vetted distribution channels until patches are deployed.
- On macOS, keep Gatekeeper set to allow apps only from the App Store or identified developers, and avoid overriding signature warnings.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
