CVE-2026-3479 in CPython
Summary
by MITRE • 03/18/2026
pkgutil.get_data() did not validate the resource argument as documented, allowing path traversals.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 05/15/2026
The vulnerability identified as CVE-2026-3479 resides within Python's pkgutil.get_data() function which failed to properly validate the resource argument as specified in its documentation. This function is designed to retrieve data from Python packages, but when processing resource paths, it did not adequately sanitize input parameters, creating a potential path traversal condition. The flaw specifically affects how the function handles resource identifiers that could contain malicious path components such as parent directory references or absolute path indicators. This issue represents a significant security concern as it allows unauthorized access to resources outside the intended package boundaries, potentially enabling attackers to read arbitrary files on the system where the Python application is running.
The technical implementation of this vulnerability stems from the improper validation of input parameters within pkgutil.get_data() which should have enforced strict path validation according to established security practices. When developers pass resource arguments to this function, they expect the system to properly handle relative paths and prevent access to files outside the package namespace. However, the lack of proper validation allows attackers to craft resource identifiers containing sequences like '../' or absolute paths that bypass intended security boundaries. This behavior directly violates the principle of least privilege and demonstrates a failure in input sanitization that aligns with CWE-22 Path Traversal vulnerabilities. The function's documentation typically specifies that resource arguments should be treated as relative paths within the package, but the implementation did not enforce this constraint.
The operational impact of CVE-2026-3479 extends beyond simple information disclosure, as it can enable more sophisticated attack vectors including arbitrary file read operations, potential privilege escalation, and system reconnaissance. An attacker who can control the resource argument passed to pkgutil.get_data() could potentially access sensitive files such as configuration files, credential stores, or system information that should remain isolated within the package's boundaries. This vulnerability particularly affects Python applications that dynamically load package resources, especially those that process user-provided data or external inputs through the package resource system. The attack surface is broad across applications that utilize Python's packaging system, including web applications, system administration tools, and any software that relies on pkgutil.get_data() for resource retrieval. The vulnerability can be exploited in environments where applications are installed with elevated privileges, potentially allowing attackers to access system files that would normally be protected by file system permissions.
Mitigation strategies for CVE-2026-3479 should focus on implementing proper input validation and sanitization within the pkgutil.get_data() function, ensuring that all resource arguments are strictly validated against expected patterns. The recommended approach includes implementing path normalization and validation routines that reject any resource identifiers containing path traversal sequences or absolute path references. Organizations should also consider applying immediate patches or updates to Python installations that address this specific vulnerability, as the fix typically involves strengthening the input validation logic within the pkgutil module. Additionally, security teams should review applications that utilize pkgutil.get_data() to ensure proper parameter validation is implemented at the application level, particularly when processing external inputs. This vulnerability demonstrates the importance of adhering to security best practices such as those outlined in the OWASP Top Ten and the MITRE ATT&CK framework, specifically addressing techniques related to path traversal and privilege escalation. System administrators should also implement monitoring for unusual file access patterns and consider restricting Python application privileges to minimize potential impact if exploitation occurs. The fix typically involves updating to a patched version of Python where the resource argument validation has been strengthened to prevent unauthorized path traversal operations.