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Mallory
UnratedPublic exploit

RCE via picklescan detection bypass for malicious pickle payloads

IdentifiersCVE-2025-71361CWE-94

CVE-2025-71361 is a remote code execution vulnerability in picklescan before version 0.0.29. The issue is described as a detection bypass in which picklescan fails to identify malicious idlelib.calltip.Calltip.fetch_tip calls embedded in pickle files. As a result, an attacker can craft a pickle payload that passes scanning but still contains executable gadget behavior. If the resulting pickle is later deserialized with Python's pickle.load(), the embedded payload can execute arbitrary code. The vulnerable condition is therefore not in pickle deserialization itself, but in picklescan's incomplete detection logic for this malicious call pattern, which can cause defenders or downstream systems to incorrectly treat a malicious pickle as safe.

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ANALYST BRIEF

Impact, mitigation & remediation

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Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can lead to arbitrary code execution in the context of the process that loads the malicious pickle via pickle.load(). This can allow compromise of the host or application performing deserialization, including execution of attacker-controlled commands, theft or modification of accessible data, installation of additional malware or persistence mechanisms, and potential lateral movement depending on the privileges and environment of the affected process.

Mitigation

If you can’t patch tonight, do this now.

Do not load untrusted pickle files with pickle.load(). Treat picklescan results as insufficient protection on vulnerable versions. Apply additional controls such as rejecting pickle inputs from external or user-controlled sources, sanitizing and tightly controlling accepted serialized content, scanning artifacts with updated tooling, and preferring safer serialization formats where practical. Restrict execution privileges of services that must process serialized data to reduce blast radius.

Remediation

Patch, then assume compromise.

Upgrade picklescan to version 0.0.29 or later, which is the referenced fixed version. Review any workflows that rely on picklescan verdicts as a trust boundary for pickle safety, and rescan or revalidate previously accepted pickle artifacts if feasible. Where possible, eliminate unsafe deserialization of pickle data from untrusted or insufficiently trusted sources.
PUBLIC EXPLOITS

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