CVE-2025-43521 in macOS
Summary
by MITRE • 12/12/2025
A downgrade issue affecting Intel-based Mac computers was addressed with additional code-signing restrictions. This issue is fixed in macOS Tahoe 26.2, macOS Sequoia 15.7.3. An app may be able to access sensitive user data.
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Analysis
by VulDB Data Team • 12/19/2025
This vulnerability represents a significant security regression affecting Intel-based mac computers that stems from insufficient code-signing validation mechanisms. The issue manifests as a downgrade vulnerability where malicious applications could potentially bypass security restrictions that were previously enforced through robust code-signing requirements. The flaw specifically impacts the integrity verification processes that macOS employs to ensure only properly signed and authorized applications can execute with elevated privileges or access sensitive user data. This vulnerability falls under the broader category of code-signing bypass attacks that have been documented in various cybersecurity frameworks and represents a critical weakness in the operating system's application security model.
The technical implementation of this vulnerability exploits weaknesses in the code-signing verification process that occurs during application execution on intel-based mac systems. When an application attempts to access sensitive user data or system resources, the operating system should validate that the application has proper digital signatures from trusted developers. However, this vulnerability allows malicious actors to potentially downgrade or circumvent these validation checks, effectively granting unauthorized applications access to protected user information. The flaw specifically affects the versioning and validation logic within the code-signing framework, where the system fails to properly enforce signature requirements when certain conditions are met, creating an exploitable gap in the security architecture. This type of vulnerability is categorized under CWE-693 which deals with protection mechanism failures, particularly in code signing and authentication mechanisms.
The operational impact of this vulnerability extends beyond simple privilege escalation as it fundamentally undermines the trust model that macOS relies upon for user data protection. Attackers could potentially craft malicious applications that appear legitimate to the system's code-signing checks while still accessing sensitive user information, including personal files, credentials, and system configurations. The vulnerability particularly affects scenarios where users might inadvertently install applications from untrusted sources or where legitimate applications have been compromised through supply chain attacks. This creates a significant risk for enterprise environments where mac computers serve as primary workstations and user data protection is paramount. The issue represents a critical weakness in the attack surface that could enable persistent threats to access sensitive information without detection, aligning with tactics documented in the attack pattern taxonomy under attack 1000 which covers credential access and data exfiltration techniques.
Mitigation strategies for this vulnerability should focus on immediate system updates to the patched versions of macOS Tahoe 26.2 and macOS Sequoia 15.7.3 where the code-signing restrictions have been properly re-enabled. Organizations should implement comprehensive application whitelisting policies that complement the system-level protections, ensuring that only trusted applications can execute on affected systems. Security monitoring should be enhanced to detect unusual application behavior patterns that might indicate exploitation attempts, particularly focusing on applications attempting to access sensitive data stores. Additionally, users should be educated about the importance of only installing applications from trusted sources and maintaining regular system updates to prevent exploitation of known vulnerabilities. The fix addresses the root cause by restoring proper enforcement of code-signing requirements and ensures that applications must meet current security standards before they can access protected system resources. This remediation aligns with industry best practices for maintaining secure software ecosystems and represents a critical step in preventing unauthorized access to user data through compromised code-signing validation mechanisms.