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October CMS stored XSS by authenticated backend user with improper configuration

Moderate severity GitHub Reviewed Published Nov 29, 2023 in octobercms/october

Package

composer october/system (Composer)

Affected versions

>= 3.0.0, < 3.5.2

Patched versions

3.5.2

Description

Impact

A user with access to the media manager that stores SVG files could create a stored XSS attack against themselves and any other user with access to the media manager when SVG files are supported.

SVG files are supported by default in v3 for convenience; however, this has resulted in multiple mistaken vulnerability reports from security researchers. As per the documentation, if a backend user is not trusted, the advice is to remove the svg extension from the list of supported file types.

Patches

The issue has been patched in v3.5.2 by including an SVG sanister. It is enabled by default for new installations but must be enabled for existing sites in the config/media.php file.

'clean_vectors' => true,

Workarounds

If you cannot upgrade for this patch, follow the pervious advice and remove svg from the supported file types.

References

Credits to:

  • Faris Krivic
  • Okan Kurtulus
  • Aldin Visnjic
  • Bug Shankar

For more information

If you have any questions or comments about this advisory:

References

@daftspunk daftspunk published to octobercms/october Nov 29, 2023
Published by the National Vulnerability Database Nov 29, 2023
Published to the GitHub Advisory Database Nov 29, 2023
Reviewed Nov 29, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

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

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(75th percentile)

Weaknesses

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Learn more on MITRE.

CVE ID

CVE-2023-44383

GHSA ID

GHSA-rvx8-p3xp-fj3p

Source code

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