Sandbox escape via various forms of "format"GHSA-xjw2-6jm9-rf67
HIGHFix: zopefoundation/RestrictedPython@4134aedGHSA-xjw2-6jm9-rf67 is a high-severity (CVSS 8.3) CWE-74 vulnerability in restrictedpython. A fix is available for restrictedpython — see the affected versions and patch details below.
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-xjw2-6jm9-rf67.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
restrictedpython🐍restrictedpythonReal-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
Impact
Python's "format" functionality allows someone controlling the format string to "read" all objects accessible through recursive attribute lookup and subscription from objects he can access. This can lead to critical information disclosure.
With RestrictedPython, the format functionality is available via the format and format_map methods of str (and unicode) (accessed either via the class or its instances) and via string.Formatter.
All known versions of RestrictedPython are vulnerable.
Patches
The issue will be fixed in 5.4 and 6.2.
Workarounds
There are no workarounds to fix the issue without upgrading.
References
- https://docs.python.org/3/library/stdtypes.html#str.format_map
- http://lucumr.pocoo.org/2016/12/29/careful-with-str-format/
- https://www.exploit-db.com/exploits/51580
For more information
If you have any questions or comments about this advisory:
- Open an issue in the RestrictedPython issue tracker
- Email us at [email protected]
Credits
Thanks for analysing and reporting the go to:
- Abhishek Govindarasu
- Ankush Menat
- Ward Theunisse
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | restrictedpython | all versions | 5.4pip install --upgrade 'restrictedpython==5.4' |
| 🐍PyPI | restrictedpython | ≥ 6.0&&< 6.2 | 6.2pip install --upgrade 'restrictedpython==6.2' |
Affected Products
restrictedpythonzopeDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for restrictedpython, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update restrictedpython to 5.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-xjw2-6jm9-rf67 is resolved across your whole dependency graph.
Workarounds
Assume what was exposed is already known: rotate any credential, token or key that the affected component could return, restrict the endpoint to callers that genuinely need it, and strip sensitive fields from responses and error output at the boundary rather than relying on the client not to read them.
Frequently Asked Questions
Is GHSA-xjw2-6jm9-rf67 in your dependencies?
Find it across PyPI, including transitive dependencies.