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Missing escaping of { in Velocity escapetool allows remote code execution

Critical
michitux published GHSA-hf43-47q4-fhq5 Apr 10, 2024

Package

maven org.xwiki.commons:xwiki-commons-velocity (Maven)

Affected versions

>= 3.0.1, < 14.10.19
>= 15.0-rc-1, < 15.5.4
>= 15.6-rc-1, < 15.9-rc-1

Patched versions

14.10.19
15.5.4
15.9-rc-1

Description

Impact

The HTML escaping of escaping tool that is used in XWiki doesn't escape {, which, when used in certain places, allows XWiki syntax injection and thereby remote code execution.

To reproduce in an XWiki installation, open <xwiki-host>/xwiki/bin/view/Panels/PanelLayoutUpdate?place=%7B%7B%2Fhtml%7D%7D%7B%7Basync%20async%3Dfalse%7D%7D%7B%7Bvelocity%7D%7D%23evaluate(%24request.eval)%7B%7B%2Fvelocity%7D%7D%7B%7B%2Fasync%7D%7D&eval=Hello%20from%20URL%20Parameter!%20I%20got%20programming%3A%20%24services.security.authorization.hasAccess(%27programming%27) where <xwiki-host> is the URL of your XWiki installation. If this displays You are not admin on this place Hello from URL Parameter! I got programming: true, the installation is vulnerable.

Patches

The vulnerability has been fixed on XWiki 14.10.19, 15.5.5, and 15.9 RC1.

Workarounds

Apart from upgrading, there is no generic workaround. However, replacing $escapetool.html by $escapetool.xml in XWiki documents fixes the vulnerability. In a standard XWiki installation, we're only aware of the document Panels.PanelLayoutUpdate that exposes this vulnerability, patching this document is thus a workaround. Any extension could expose this vulnerability and might thus require patching, too.

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
None
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:N/UI:N/S:C/C:H/I:H/A:H

CVE ID

CVE-2024-31996

Weaknesses

Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')

The product receives input from an upstream component, but it does not neutralize or incorrectly neutralizes code syntax before using the input in a dynamic evaluation call (e.g. eval). Learn more on MITRE.