CVE-2020-9934 in macOS
Summary
by MITRE • 10/16/2020
An issue existed in the handling of environment variables. This issue was addressed with improved validation. This issue is fixed in iOS 13.6 and iPadOS 13.6, macOS Catalina 10.15.6. A local user may be able to view sensitive user information.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 01/29/2025
The vulnerability identified as CVE-2020-9934 represents a critical flaw in how operating systems handle environment variables, specifically within the iOS and macOS ecosystems. This issue stems from insufficient validation mechanisms that allow malicious actors to exploit improper handling of user environment data. The vulnerability affects versions prior to iOS 13.6, iPadOS 13.6, and macOS Catalina 10.15.6, indicating a widespread impact across Apple's mobile and desktop platforms. The flaw operates at the system level where environment variables are processed and managed, creating potential entry points for unauthorized information disclosure.
The technical implementation of this vulnerability involves the improper sanitization and validation of environment variables that applications and system processes rely upon. When environment variables contain malformed or unexpected data, the system fails to properly validate the inputs before processing them, leading to potential information exposure. This type of vulnerability aligns with CWE-20, which describes improper input validation, and represents a classic example of how insufficient data sanitization can create security weaknesses. The flaw specifically impacts the way the operating system parses and handles environment variable values, potentially allowing a local attacker to manipulate these variables to extract sensitive user information.
From an operational perspective, this vulnerability presents significant risks for user privacy and system security. A local user with minimal privileges can exploit this weakness to access sensitive information that should normally be protected within the system's environment variable handling mechanisms. The impact extends beyond simple information disclosure, as environment variables often contain critical system paths, user identifiers, and other sensitive configuration data. This type of vulnerability can be leveraged as part of broader attack chains, potentially enabling privilege escalation or lateral movement within compromised systems. The ATT&CK framework categorizes this under privilege escalation techniques where initial access can be used to gain deeper system insights through environment manipulation.
The remediation for CVE-2020-9934 involved implementing enhanced validation mechanisms within the operating system's environment variable processing routines. Apple addressed this by strengthening input validation checks and improving the sanitization of environment variable data before system processes utilize these values. The fix ensures that environment variables undergo proper validation before being processed, preventing malformed or maliciously crafted inputs from causing information disclosure. Organizations should prioritize updating to iOS 13.6, iPadOS 13.6, and macOS Catalina 10.15.6 to mitigate this risk. Security teams should also implement monitoring for unusual environment variable access patterns and consider additional defensive measures such as environment variable hardening and process isolation techniques to further reduce the attack surface. The vulnerability serves as a reminder of the importance of robust input validation in system-level components and the potential consequences of inadequate sanitization of user-controlled data.