Sandbox escape via various forms of "format".
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 security@plone.org
Credits
Thanks for analysing and reporting the go to:
- Abhishek Govindarasu
- Ankush Menat
- Ward Theunisse
Affected software
Click a technology to see all vulnerabilities affecting it.
| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Python (PyPI) | restrictedpython | < 5.4, >= 6.0, < 6.2 | 5.4, 6.2 |
References
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:L- Weakness (CWE)
CWE-74- Platform
- Python (PyPI)
- Package
restrictedpython- Disclosed
- 30.08.2023
- Updated
- 11.10.2026 11:19
Sources and licenses
OSV / GitHub Advisory Database - PYSEC-2023-159 - PyPA Advisory Database; CC BY 4.0
OSV / GitHub Advisory Database - GHSA-xjw2-6jm9-rf67 - CC BY 4.0
Vulnerability history: restrictedpython
All published vulnerabilities of this package (Python (PyPI)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 6
- First → latest
- 07.2023 09.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 6
Disclosures per year
- 2023: 2
- 2024: 1
- 2025: 1
- 2026: 2
-
Sandbox escape via various forms of "format". this entry
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