GHSA-hm2p-fhwx-9285 CVE-2021-33509 PYSEC-2021-81

Incorrect Permission Assignment for Critical Resource in Plone

Critical PyPI

Severity: 0.0 / 10; Critical · CVSS 4.0
Exploit chance (EPSS): 1.98%; Chance of exploitation in the next 30 days. Higher than 80.54% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-732 Incorrect Permission Assignment for Critical Resource
Fix: 5.2.5; Upgrade plone to this version or later

Description

Plone through 5.2.4 allows remote authenticated managers to perform disk I/O via crafted keyword arguments to the ReStructuredText transform in a Python script.

Affected versions

PyPI

Package	Vulnerable	Fixed in
plone	`< 5.2.5`	`5.2.5`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

plone PyPI → `5.2.5`

pip

pip install --upgrade "plone>=5.2.5"

poetry

poetry add "plone>=5.2.5"

uv

uv add "plone>=5.2.5"

Severity breakdown

CVSS 4.0 0.0

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Attack vector: Network
Attack complexity: Low
Attack requirements: None
Privileges required: Low
User interaction: None
Confidentiality (vulnerable system): High
Integrity (vulnerable system): High
Availability (vulnerable system): High
Confidentiality (subsequent systems): High
Integrity (subsequent systems): High
Availability (subsequent systems): High

CVSS 3.1 9.9

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

Attack vector: Network
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: Changed
Confidentiality: High
Integrity: High
Availability: High

Weakness

CWE-732: Incorrect Permission Assignment for Critical Resource

The product specifies permissions for a security-critical resource in a way that allows that resource to be read or modified by unintended actors.

How to prevent it

Implementation: When using a critical resource such as a configuration file, check to see if the resource has insecure permissions (such as being modifiable by any regular user) [REF-62], and generate an error or even exit the software if there is a possibility that the resource could have been modified by an unauthorized party.
Architecture and Design: Divide the software into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully defining distinct user groups, privileges, and/or roles. Map these against data, functionality, and the related resources. Then set the permissions accordingly. This will allow you to maintain more fine-grained control over your resources. [REF-207]
Architecture and Design, Operation: Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software. OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
Implementation, Installation: During program startup, explicitly set the default permissions or umask to the most restrictive setting possible. Also set the appropriate permissions during program installation. This will prevent you from inheriting insecure permissions from any user who installs or runs the program.
System Configuration: For all configuration files, executables, and libraries, make sure that they are only readable and writable by the software's administrator.
Documentation: Do not suggest insecure configuration changes in documentation, especially if those configurations can extend to resources and other programs that are outside the scope of the application.
Installation: Do not assume that a system administrator will manually change the configuration to the settings that are recommended in the software's manual.
Operation, System Configuration: Ensure that the software runs properly under the United States Government Configuration Baseline (USGCB) [REF-199] or an equivalent hardening configuration guide, which many organizations use to limit the attack surface and potential risk of deployed software.
Implementation, System Configuration, Operation: When storing data in the cloud (e.g., S3 buckets, Azure blobs, Google Cloud Storage, etc.), use the provider's controls to disable public access.

References

Advisories

Packages

github.com/plone/Plone

Timeline

May 21, 2021 Published
Oct 18, 2024 Last updated by the source
Nov 1, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-xg5p-8wg5-rhxm Phone information disclosure vulnerability	High	Also affects plone
GHSA-5xfx-55x4-j223 Cross-Frame Scripting vulnerability has been found on Plone CMS	High	Also affects plone
GHSA-47p5-p3jw-w78w Server-Side Request Forgery in Plone CMS	High	Also affects plone
GHSA-cvwc-g7fw-7xrj Plone XSS Vulnerability	Medium	Also affects plone
GHSA-pwgm-jvqv-6v8p Plone anonymous access to sub-objects in CMFEditions where KwAsAttributes classes were publishable	High	Also affects plone
GHSA-46f9-f8jm-mw2x Plone Cross-site Scripting vulnerability in the LiveSearch module	Medium	Also affects plone
GHSA-hjp5-hv33-q58g Plone credentials stored in session cookie	Medium	Also affects plone
GHSA-593c-j348-f3gv Plone Improper Session Management	High	Also affects plone

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