PickleScan <0.0.23 ZIP Flag Bypass Leading to PyTorch Model RCE (CVE-2025-1945)

CVE-2025-1945 Summary PickleScan before 0.0.23 fails to detect malicious pickle files inside PyTorch model archives when certain ZIP file flag bits are modified. By flipping specific bits in the ZIP file headers, an attacker can embed malicious pickle files that remain undetected by PickleScan while still being successfully loaded by PyTorch's torch.load(). This can lead to arbitrary code execution when loading a compromised model. Severity Rating CVSS Score: 5.3 Severity: Medium Description PickleScan relies on Python's zipfile module to extract and scan files within ZIP-based model archives. However, certain flag bits in ZIP headers affect how files are interpreted, and some of these bits cause PickleScan to fail while leaving PyTorch's loading mechanism unaffected. Proof-of-Concept (PoC) The code example demonstrates how a crafted ZIP file could bypass PickleScan's security scan to load malicious model(s). Impact Who is impacted? Any organization or user relying on PickleScan to detect malicious pickle files inside PyTorch models. What is the impact? Attackers can embed malicious pickle payloads inside PyTorch models that evade PickleScan's detection but still execute upon loading. Potential Exploits: This vulnerability could be exploited in machine learning supply chain attacks. Mitigations 1. Improve ZIP Handling: PickleScan should use a more relaxed ZIP parser that continues processing when encountering modified flag bits. 2. Scan All Embedded Files Regardless of Flags: Ensure that files with altered metadata are still extracted and analyzed. Credits Trevor Madge (@madgetr) of Sonatype Note PickleScan version 0.0.23 contains a fix for this issue and can be upgraded to.

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PickleScan <0.0.23 ZIP Flag Bypass Leading to PyTorch Model RCE (CVE-2025-1945)