CVE-2026-33139 — pyspector
CVE-2026-33139 is a CWE-184 vulnerability in pyspector. A fix is available for pyspector — see the affected versions and patch details below.
PySpector has a Plugin Sandbox Bypass leads to Arbitrary Code Execution
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.
- 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-2026-33139.
EPSS Exploitation Probability
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
pyspectorReal-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
Summary
PySpector versions <= 0.1.6 are affected by a security validation bypass in the plugin system. The validate_plugin_code() function in plugin_system.py, performs static AST analysis to block dangerous API calls before a plugin is trusted and executed. However, the internal resolve_name() helper only handles ast.Name and ast.Attribute node types, returning None for all others. When a plugin uses indirect function calls via getattr() (such as getattr(os, 'system')) the outer call's func node is of type ast.Call, causing resolve_name() to return None, and the security check to be silently skipped. The plugin incorrectly passes the trust workflow, and executes arbitrary system commands on the user's machine when loaded.
Impact
An attacker who can deliver a malicious plugin file to a PySpector user and convince them to install it, can achieve arbitrary code execution on the user's local machine. Exploitation requires the victim to explicitly run pyspector plugin install --trust on the malicious file (a deliberate multi-step action that meaningfully limits the attack surface compared to passive vulnerabilities). However, the bypass directly undermines the security guarantee that validate_plugin_code() is designed to provide. Once the plugin is trusted and executed, the following is achievable:
- Full read/write access to the local filesystem
- Exfiltration of sensitive data and environment variables (i.e. API keys, credentials, etc...)
- Establishment of persistence mechanisms
- Lateral movement in CI/CD environments where PySpector runs with elevated permissions (pre-commit hooks and scheduled scans)
Any user of PySpector who installs third-party plugins outside the official repository is potentially affected.
PoC
The following steps reproduce the vulnerability on PySpector <= 0.1.6:
- Create a malicious plugin file that uses getattr-based indirect calls to bypass AST validation, and confirm the validator incorrectly marks it as safe: <img width="1300" height="675" alt="image" src="https://github.com/user-attachments/assets/4de3a0d1-1c77-4454-ad10-2369d5ca9997" />
- Run PySpector Plugin Validator module (this confirms the validator incorrectly marks the plugin as safe): <img width="908" height="239" alt="image" src="https://github.com/user-attachments/assets/3e3b9603-4d95-4a39-be97-4163f6639599" />
- Install and trust the plugin through the normal PySpector workflow:
pyspector plugin install /tmp/evil_plugin.py --trust
4. Execute the plugin, during a scan:
pyspector scan /any/target --plugin evil
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | pyspector | all versions | 0.1.7pip install --upgrade 'pyspector==0.1.7' |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pyspector, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update pyspector to 0.1.7 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-33139 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-2026-33139 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-33139. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-33139 in your dependencies?
O3 Security finds CVE-2026-33139 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.