CVE-2006-4980 in Python
Summary
by MITRE
Buffer overflow in the repr function in Python 2.3 through 2.6 before 20060822 allows context-dependent attackers to cause a denial of service and possibly execute arbitrary code via crafted wide character UTF-32/UCS-4 strings to certain scripts.
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Analysis
by VulDB Data Team • 04/23/2026
The vulnerability identified as CVE-2006-4980 represents a critical buffer overflow flaw within Python's internal representation function known as repr. This issue affects Python versions 2.3 through 2.6, specifically before the patch release of August 22, 2006, making it a significant concern for systems running these older Python versions. The vulnerability stems from improper handling of wide character UTF-32/UCS-4 encoded strings during the repr function's processing, creating a scenario where malicious input can trigger unintended behavior in the interpreter's memory management.
The technical exploitation of this vulnerability occurs when the repr function encounters crafted UTF-32/UCS-4 strings that contain specially constructed wide character sequences. These strings, when processed by Python's internal representation mechanism, cause the function to write beyond allocated memory boundaries, resulting in a buffer overflow condition. The flaw specifically manifests in how Python handles character encoding conversions and memory allocation for string representation operations, creating a predictable pattern of memory corruption that can be leveraged by attackers. This issue is classified as a buffer overflow under CWE-121, which specifically addresses conditions where insufficient space is allocated for data, leading to memory corruption. The vulnerability's context-dependent nature means that the attack requires specific conditions to be met, typically involving the processing of malformed UTF-32/UCS-4 encoded input through Python scripts that utilize the repr function.
The operational impact of this vulnerability extends beyond simple denial of service to potentially enabling arbitrary code execution, making it particularly dangerous for systems running vulnerable Python versions. When exploited, the buffer overflow can cause Python interpreters to crash, resulting in service disruption, or more seriously, allow attackers to inject and execute malicious code within the context of the running Python process. This capability represents a significant threat to system security, particularly in environments where Python applications process untrusted input data, such as web applications, network services, or any system handling user-provided content. The vulnerability affects the fundamental operation of Python's string handling mechanisms and can be triggered through various attack vectors including file processing, network input handling, or any scenario where the repr function processes potentially malicious UTF-32/UCS-4 encoded strings.
Mitigation strategies for CVE-2006-4980 primarily focus on immediate remediation through patching or upgrading to secure Python versions. System administrators should prioritize updating to Python 2.6.1 or later releases that contain the appropriate fixes for this vulnerability. Additionally, implementing input validation and sanitization measures can provide temporary protection while patches are deployed, particularly focusing on filtering or rejecting UTF-32/UCS-4 encoded strings that might trigger the vulnerable code paths. Organizations should also consider implementing runtime protections such as address space layout randomization and stack canaries to reduce the effectiveness of potential exploitation attempts. From an operational security perspective, this vulnerability aligns with ATT&CK technique T1059.006 for command and scripting interpreter, as attackers could leverage the arbitrary code execution capability to establish persistent access or escalate privileges within affected systems. The vulnerability underscores the importance of regular security updates and proper input validation practices in preventing exploitation of memory corruption vulnerabilities that can lead to complete system compromise.