Fickling Blocklist Bypass: cProfile.run()
Date: 2026-01
Affected: pip/fickling
Attack vector: deserialization
Category: vulnerability-disclosure
Severity: High
CVE: CVE-2025-67748
CVE-2026-22606
CVE-2026-22607
CWE: CWE-184
CWE-502
CWE-94

# Fickling's assessment `cProfile` was added to the list of unsafe imports (https://github.com/trailofbits/fickling/commit/dc8ae12966edee27a78fe05c5745171a2b138d43). # Original report ## Description ### Summary Fickling versions up to and including 0.1.6 do not treat Python's `cProfile` module as unsafe. Because of this, a malicious pickle that uses `cProfile.run()` is classified as SUSPICIOUS instead of OVERTLY_MALICIOUS. If a user relies on Fickling's output to decide whether a pickle is safe to deserialize, this misclassification can lead them to execute attacker-controlled code on their system. This affects any workflow or product that uses Fickling as a security gate for pickle deserialization. ### Details The `cProfile` module is missing from fickling's block list of unsafe module imports in `fickling/analysis.py`. This is the same root cause as CVE-2025-67748 (pty) and CVE-2025-67747 (marshal/types). Incriminated source code: - File: `fickling/analysis.py` - Class: `UnsafeImports` - Issue: The blocklist does not include `cProfile`, `cProfile.run`, or `cProfile.runctx` Reference to similar fix: - PR #187 added `pty` to the blocklist to fix CVE-2025-67748 - PR #108 documented the blocklist approach - The same fix pattern should be applied for `cProfile` How the bypass works: 1. Attacker creates a pickle using `cProfile.run()` in `__reduce__` 2. `cProfile.run()` accepts a Python code string and executes it directly (C-accelerated version of profile.run) 3.


Mitigations:

Architectural layers (MAESTRO):