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Persisted Cross-Site Scripting in Frontend Rendering

High
ohader published GHSA-r4f8-f93x-5qh3 Feb 7, 2023

Package

composer typo3/cms-core (Composer)

Affected versions

8.7.0-8.7.50, 9.0.0-9.5.39, 10.0.0-10.4.34, 11.0.0-11.5.22, 12.0.0-12.1.3

Patched versions

8.7.51, 9.5.40, 10.4.36, 11.5.23, 12.2.0

Description

CVSS: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L/E:F/RL:O/RC:C (8.2)

Problem

TYPO3 core component GeneralUtility::getIndpEnv() uses the unfiltered server environment variable PATH_INFO, which allows attackers to inject malicious content.

In combination with the TypoScript setting config.absRefPrefix=auto, attackers can inject malicious HTML code into pages that have not yet been rendered and cached. As a result, injected values would be cached and delivered to other website visitors (persisted cross-site scripting).

Individual code which relies on the resolved value of GeneralUtility::getIndpEnv('SCRIPT_NAME') and corresponding usages (as shown below) are vulnerable as well.

  • GeneralUtility::getIndpEnv('PATH_INFO')
  • GeneralUtility::getIndpEnv('SCRIPT_NAME')
  • GeneralUtility::getIndpEnv('TYPO3_REQUEST_DIR')
  • GeneralUtility::getIndpEnv('TYPO3_REQUEST_SCRIPT')
  • GeneralUtility::getIndpEnv('TYPO3_SITE_PATH')
  • GeneralUtility::getIndpEnv('TYPO3_SITE_SCRIPT')
  • GeneralUtility::getIndpEnv('TYPO3_SITE_URL')

Installations of TYPO3 versions 8.7 and 9.x are probably only affected when server environment variable TYPO3_PATH_ROOT is defined - which is the case if they were installed via Composer.

Additional investigations confirmed that Apache and Microsoft IIS web servers using PHP-CGI (FPM, FCGI/FastCGI, or similar) are affected. There might be the risk that nginx is vulnerable as well. It was not possible to exploit Apache/mod_php scenarios.

Solution

The usage of server environment variable PATH_INFO has been removed from corresponding processings in GeneralUtility::getIndpEnv(). Besides that, the public property TypoScriptFrontendController::$absRefPrefix is encoded for both being used as a URI component and for being used as a prefix in an HTML context. This mitigates the cross-site scripting vulnerability.

Update to TYPO3 versions 8.7.51 ELTS, 9.5.40 ELTS, 10.4.36 LTS, 11.5.23 LTS and 12.2.0 that fix the problem described above.

ℹ️ Strong security defaults - Manual actions required
Any web server using PHP-CGI (FPM, FCGI/FastCGI, or similar) needs to ensure that the PHP setting cgi.fix_pathinfo=1 is used, which is the default PHP setting. In case this setting is not enabled, an exception is thrown to avoid continuing with invalid path information.

For websites that cannot be patched timely the TypoScript setting config.absRefPrefix at least should be set to a static path value, instead of using auto - e.g. config.absRefPrefix=/ - this does not fix all aspects of the vulnerability, and is just considered to be an intermediate mitigation to the most prominent manifestation.

Credits

Thanks to Lars Michalowski, Kevin Andrews & Robin Martin who reported this issue, and to TYPO3 core team members Benjamin Franzke & Helmut Hummel who fixed the issue.

References

Severity

High

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
Required
Scope
Changed
Confidentiality
Low
Integrity
High
Availability
Low

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:R/S:C/C:L/I:H/A:L

CVE ID

CVE-2023-24814

Weaknesses

Credits