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Remote code execution from account via custom skins support

Critical
surli published GHSA-cv55-v6rw-7r5v Apr 10, 2024

Package

maven org.xwiki.platform:xwiki-platform-oldcore (Maven)

Affected versions

>= 6.4-milestone-1, < 14.10.19
>= 15.0-rc-1, < 15.5.4
>= 15.6-rc-1, < 15.10-rc-1

Patched versions

14.10.19
15.5.4
15.10-rc-1

Description

Impact

Any user who can edit any page like their profile can create a custom skin with a template override that is executed with programming right, thus allowing remote code execution.

To reproduce, as a user without edit, script or admin right, add an object of class XWiki.XWikiSkins to your profile. Name it whatever you want and set the Base Skin to flamingo.
Add an object of class XWikiSkinFileOverrideClass and set the path to macros.vm and the content to:

#macro(mediumUserAvatar $username)
  #resizedUserAvatar($username 50)
  $services.logging.getLogger('Skin').error("I got programming: $services.security.authorization.hasAccess('programming')")
#end

Back to your profile, click Test this skin. Force a refresh, just in case.
If the error "Skin - I got programming: true" gets logged, the installation is vulnerable.

Patches

This has been patched in XWiki 14.10.19, 15.5.4 and 15.10RC1.

Workarounds

We're not aware of any workaround except upgrading.

References

Severity

Critical

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
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

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:N/S:C/C:H/I:H/A:H

CVE ID

CVE-2024-31987

Weaknesses

Missing Authorization

The product does not perform an authorization check when an actor attempts to access a resource or perform an action. Learn more on MITRE.