Pillow is a Python imaging library. Prior to 13.0.0, the TarIO initializer in src/PIL/TarIO.py accepts a negative octal member size and computes a backward seek that returns to the same 512-byte header. When the requested member name does not match, the parser repeatedly reads that header, consumes a full CPU core, and never returns. TarIO is reached only when an application directly uses PIL.TarIO.TarIO rather than the default Image.open() path. This issue is fixed in version 13.0.0.
This vulnerability carries a MEDIUM severity rating with a CVSS v3.1 score of 6.5, indicating it can be exploited remotely over the network with relatively low complexity though user interaction is required and does not require pre-existing privileges . The vulnerability impacts and availability (service disruption) for affected systems. Impacting 1 product from python organizations running these solutions should prioritize assessment and patching.
Reported in 2026, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.
2026-10-21T21:20:32.650
2026-10-30T17:17:32.240
Modified
CVSSv3.1: 6.5 (MEDIUM)
SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For python's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.