8.3

CVSS Score

3.1

Basic Information

CVE ID

CVE-2023-41039

GHSA ID

GHSA-xjw2-6jm9-rf67

EPSS Score

0.24641%

CWE

CWE-74

Published

8/30/2023

Updated

11/7/2023

KEV Status

Technology

Python

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CVE-2023-41039

CVE-2023-41039: 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

(GitHub Advisory)

8.3

CVSS Score

3.1

Basic Information

CVE ID

CVE-2023-41039

GHSA ID

GHSA-xjw2-6jm9-rf67

EPSS Score

0.24641%

CWE

CWE-74

Published

8/30/2023

Updated

11/7/2023

KEV Status

Technology

Python

Technical Details

CVSS Vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:L

Package Name	Ecosystem	Vulnerable Versions	First Patched Version
RestrictedPython	pip	<= 5.3	5.4
RestrictedPython	pip	>= 6.0, <= 6.1	6.2

Vulnerability Intelligence
Miggo AI

Root Cause Analysis

The vulnerability stems from three key points:

The commit modifies Guards.py to block 'format'/'format_map' on str/unicode instances and classes, indicating these methods were previously accessible.
The Utilities.py patch replaces direct 'string' module access with a delegator that specifically blocks 'Formatter', showing it was previously exposed.
Test cases demonstrate exploitation via str.format(), str.format_map(), and string.Formatter access. The CWE-74 classification confirms this is an injection vulnerability where format strings act as the injection vector for attribute traversal.

Vulnerable functions

Only Mi**o us*rs **n s** t*is s**tion

WAF Protection Rules

WAF Rule

### Imp**t Pyt*on's "*orm*t" *un*tion*lity *llows som*on* *ontrollin* t** *orm*t strin* to "r***" *ll o*j**ts ****ssi*l* t*rou** r**ursiv* *ttri*ut* lookup *n* su*s*ription *rom o*j**ts ** **n ****ss. T*is **n l*** to *riti**l in*orm*tion *is*losur*.

Reasoning

T** vuln*r**ility st*ms *rom t*r** k*y points: *. T** *ommit mo*i*i*s *u*r*s.py to *lo*k '*orm*t'/'*orm*t_m*p' on str/uni*o** inst*n**s *n* *l*ss*s, in*i**tin* t**s* m*t*o*s w*r* pr*viously ****ssi*l*. *. T** Utiliti*s.py p*t** r*pl***s *ir**t 'strin

8.3

Basic Information

Concerned about an active attack path?

CVE-2023-41039: Sandbox escape via various forms of "format".

Impact

Patches

Workarounds

References

For more information

Credits

8.3

Basic Information

Technical Details

Vulnerability IntelligenceMiggo AI

Root Cause Analysis

Vulnerable functions

WAF Protection Rules

WAF Rule

Reasoning

Vulnerability Intelligence
Miggo AI