Calling unserialize() on malicious user-submitted content can result in the following scenarios: - trigger deletion of arbitrary directory in file system (if writable for web server) - trigger message submission via email using identity of web site (mail relay)

Another insecure deserialization vulnerability is required to actually exploit mentioned aspects.

Update to TYPO3 versions 9.5.17 or 10.4.2 that fix the problem described.

References https://typo3.org/security/advisory/typo3-core-sa-2020-004

Possible Arbitrary Code Execution in Image Processing

### Meta CVSS: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C (8.2) CWE-325, CWE-20, CWE-200, CWE-502

Problem It has been discovered that an internal verification mechanism can be used to generate arbitrary checksums. This allows to inject arbitrary data having a valid cryptographic message authentication code (HMAC-SHA1) and can lead to various attack chains as described below.

TYPO3-CORE-SA-2020-007, CVE-2020-15099: Potential Privilege Escalation + the database server used for a TYPO3 installation must be accessible for an attacker (either via internet or shared hosting network) + CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C (7.5, high) TYPO3-CORE-SA-2016-013, CVE-2016-5091: Insecure Deserialization & Remote Code Execution + an attacker must have access to at least one Extbase plugin or module action in a TYPO3 installation + CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C (9.1, critical)

The overall severity of this vulnerability is high (8.2) based on mentioned attack chains and the requirement of having a valid backend user session (authenticated).

Solution Update to TYPO3 versions 9.5.20 or 10.4.6 that fix the problem described.

Credits Thanks to TYPO3 security team member Oliver Hader who reported and fixed the issue.

References TYPO3-CORE-SA-2020-008

In TYPO3 CMS 9.0.0 through 9.5.16 and 10.0.0 through 10.4.1, it has been discovered that backend user settings (in $BEUSER->uc) are vulnerable to insecure deserialization. In combination with vulnerabilities of third party components, this can lead to remote code execution. A valid backend user account is needed to exploit this vulnerability. This has been fixed in 9.5.17 and 10.4.2.

### Meta CVSS v3.1: AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C CWE-352 CWE-346

Problem It has been discovered that backend user interface and install tool are vulnerable to same-origin request forgery. A backend user can be tricked into interacting with a malicious resource an attacker previously managed to upload to the web server - scripts are then executed with the privileges of the victims' user session.

In a worst case scenario new admin users can be created which can directly be used by an attacker. The vulnerability is basically a cross-site request forgery (CSRF) triggered by a cross-site scripting vulnerability (XSS) - but happens on the same target host - thus, it’s actually a same-origin request forgery.

Malicious payload such as HTML containing JavaScript might be provided by either an authenticated backend user or by a non-authenticated user using a 3rd party extension - e.g. file upload in a contact form with knowing the target location.

The attacked victim requires an active and valid backend or install tool user sessions at the time of the attack to be successful.

Solution Update to TYPO3 versions 9.5.17 or 10.4.2 that mitigates the problem described.

Additional Considerations

The deployment of additional mitigation techniques is suggested as described below.

Sudo Mode Extension

This TYPO3 extension intercepts modifications to security relevant database tables, e.g. those storing user accounts or storages of the file abstraction layer. Modifications need to confirmed by again by the acting user with providing their password again - this technique is known as "sudo mode". This way unintended actions happening in the background can be mitigated.

https://github.com/FriendsOfTYPO3/sudo-mode https://extensions.typo3.org/extension/sudomode

Content Security Policy

Content Security Policies tell (modern) browsers how resources served a particular site are handled - it also it possible to disallow script executions for specific locations. In a TYPO3 context it is suggested to disallow direct script execution at least for locations /fileadmin/ and /uploads/.

in fileadmin/.htaccess <IfModule modheaders.c> Header add Content-Security-Policy "default-src 'self'; script-src 'none';" </IfModule>

Credits Thanks to Matteo Bonaker who reported this issue and to TYPO3 security team member Oliver Hader who fixed the issue.

References https://typo3.org/security/advisory/typo3-core-sa-2020-006

An issue was discovered in TYPO3 before 8.7.30, 9.x before 9.5.12, and 10.x before 10.2.2. It has been discovered that the classes QueryGenerator and QueryView are vulnerable to insecure deserialization. One exploitable scenario requires having the system extension ext:lowlevel (Backend Module: DB Check) installed, with a valid backend user who has administrator privileges. The other exploitable scenario requires having the system extension ext:sysaction installed, with a valid backend user who has limited privileges.

TYPO3 is a free and open source Content Management Framework released under the GNU General Public License. In affected versions the TYPO3 core component GeneralUtility::getIndpEnv() uses the unfiltered server environment variable PATHINFO, which allows attackers to inject malicious content. In combination with the TypoScript setting config.absRefPrefix=auto, attackers can inject malicious HTML code to pages that have not been rendered and cached, yet. 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('SCRIPTNAME') and corresponding usages (as shown below) are vulnerable as well. Additional investigations confirmed that at least Apache web server deployments using CGI (FPM, FCGI/FastCGI, and similar) are affected. However, there still might be the risk that other scenarios like nginx, IIS, or Apache/modphp are vulnerable. The usage of server environment variable PATHINFO 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. Users are advised to update to TYPO3 versions 8.7.51 ELTS, 9.5.40 ELTS, 10.4.35 LTS, 11.5.23 LTS and 12.2.0 which fix this problem. For users who are unable to patch in a timely manner the TypoScript setting config.absRefPrefix should at least be set to a static path value, instead of using auto - e.g. config.absRefPrefix=/. This workaround does not fix all aspects of the vulnerability, and is just considered to be an intermediate mitigation to the most prominent manifestation.

TYPO3 is an open source PHP based web content management system. Versions prior to 8.7.49, 9.5.38, 10.4.33, 11.5.20, and 12.1.1 are vulnerable to Code Injection. Due to the lack of separating user-submitted data from the internal configuration in the Form Designer backend module, it is possible to inject code instructions to be processed and executed via TypoScript as PHP code. The existence of individual TypoScript instructions for a particular form item and a valid backend user account with access to the form module are needed to exploit this vulnerability. This issue is patched in versions 8.7.49 ELTS, 9.5.38 ELTS, 10.4.33, 11.5.20, 12.1.1.

Insecure Deserialization in TYPO3 CMS

Problem Due to the lack of ensuring file extensions belong to configured allowed mime-types, attackers can upload arbitrary data with arbitrary file extensions - however, default fileDenyPattern successfully blocked files like .htaccess or malicious.php.

TYPO3 Extbase extensions, which implement a file upload and do not implement a custom TypeConverter to transform uploaded files into FileReference domain model objects are affected by the vulnerability as well, since the UploadedFileReferenceConverter of ext:form handles the file upload and will accept files of any mime-type which are persisted to the default location.

In any way, uploaded files are placed in the default location /fileadmin/userupload/, in most scenarios keeping the submitted filename - which allows attackers to directly reference files, or even correctly guess filenames used by other individuals, disclosing this information.

No authentication is required to exploit this vulnerability.

Solution Update to TYPO3 versions 8.7.40, 9.5.25, 10.4.14, 11.1.1 that fix the problem described.

Type converter UploadedFileReferenceConverter is not registered globally anymore and just handles uploaded files within the scope of the Form Framework. Guessable storage location has changed from /fileadmin/userupload/form\\<random-hash\>/ to /fileadmin/formuploads/<random-40-bit>. Allowed mime-types must match expected file extensions (e.g. application/pdf must be .pdf, and cannot be .html).

Extbase extensions, who rely on the global availability of the UploadedFileReferenceConverter must now implement a custom TypeConverter to handle file uploads or explicitly implement the ext:form UploadedFileReferenceConverter with appropriate setting for accepted mime-types.

Credits Thanks to Sebastian Michaelsen, Marc Lindemann, Oliver Eglseder, Markus Volkmer, Jakob Kunzmann, Johannes Regner, Richie Lee who reported this issue, and to TYPO3 core & security team members Oliver Hader & Benni Mack, as well as TYPO3 contributor Ralf Zimmermann who fixed the issue.

References TYPO3-CORE-SA-2021-002

Problem Due to improper input validation, attackers can by-pass restrictions of predefined options and submit arbitrary data in the Form Designer backend module of the Form Framework.

In the default configuration of the Form Framework this allows attackers to explicitly allow arbitrary mime-types for file uploads - however, default fileDenyPattern successfully blocked files like .htaccess or malicious.php. Besides that, attackers can persist those files in any writable directory of the corresponding TYPO3 installation.

A valid backend user account with access to the form module is needed to exploit this vulnerability.

Solution Update to TYPO3 versions 8.7.40, 9.5.25, 10.4.14, 11.1.1 that fix the problem described.

Credits Thanks to Richie Lee who reported this issue and to TYPO3 contributor Ralf Zimmermann who fixed the issue.

References TYPO3-CORE-SA-2021-003

### Meta CVSS: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H/E:F/RL:O/RC:C (7.5) CWE-20, CWE-200

Problem In case an attacker manages to generate a valid cryptographic message authentication code (HMAC-SHA1) - either by using a different existing vulnerability or in case the internal encryptionKey was exposed - it is possible to retrieve arbitrary files of a TYPO3 installation. This includes the possibility to fetch typo3conf/LocalConfiguration.php which again contains the encryptionKey as well as credentials of the database management system being used.

In case a database server is directly accessible either via internet or in a shared hosting network, this allows to completely retrieve, manipulate or delete database contents. This includes creating an administration user account - which can be used to trigger remote code execution by injecting custom extensions.

Solution Update to TYPO3 versions 9.5.20 or 10.4.6 that fix the problem described.

Credits Thanks to TYPO3 security team member Oliver Hader who reported and fixed the issue.

References TYPO3-CORE-SA-2020-007

TYPO3 is an open source PHP based web content management system. In TYPO3 before versions 9.5.23 and 10.4.10 user session identifiers were stored in cleartext - without processing with additional cryptographic hashing algorithms. This vulnerability cannot be exploited directly and occurs in combination with a chained attack - like for instance SQL injection in any other component of the system. Update to TYPO3 versions 9.5.23 or 10.4.10 that fix the problem described.

TYPO3 is an open source PHP based web content management system. In versions prior to 9.5.38, 10.4.33, 11.5.20, and 12.1.1, requesting invalid or non-existing resources via HTTP triggers the page error handler, which again could retrieve content to be shown as an error message from another page. This leads to a scenario in which the application is calling itself recursively - amplifying the impact of the initial attack until the limits of the web server are exceeded. This vulnerability is very similar, but not identical, to the one described in CVE-2021-21359. This issue is patched in versions 9.5.38 ELTS, 10.4.33, 11.5.20 or 12.1.1.

Problem User session identifiers were stored in cleartext - without processing of additional cryptographic hashing algorithms. This vulnerability cannot be exploited directly and occurs in combination with a chained attack - like for instance SQL injection in any other component of the system.

Solution Update to TYPO3 versions 6.2.57, 7.6.51, 8.7.40, 9.5.25, 10.4.14, 11.1.1 that fix the problem described.

Credits Thanks to TYPO3 security team member Oliver Hader who reported this issue and to TYPO3 core & security team members Benni Mack & Oliver Hader who fixed the issue.

References TYPO3-CORE-SA-2021-006

### Meta CVSS: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H/E:F/RL:O/RC:C (5.5) CWE-405, CWE-674 Status: DRAFT

Problem Requesting invalid or non-existing resources via HTTP triggers the page error handler which again could retrieve content to be shown as error message from another page. This leads to a scenario in which the application is calling itself recursively - amplifying the impact of the initial attack until the limits of the web server are exceeded.

Solution Update to TYPO3 versions 9.5.25, 10.4.14, 11.1.1 that fix the problem described.

Credits Thanks to Paul Keller, Mathias Bolt Lesniak and Kay Strobach who reported this issue and to TYPO3 framework merger Frank Nägler and to TYPO3 security team member Torben Hansen who fixed the issue.

References TYPO3-CORE-SA-2021-005

An issue was discovered in TYPO3 before 8.7.30, 9.x before 9.5.12, and 10.x before 10.2.2. Because escaping of user-submitted content is mishandled, the class QueryGenerator is vulnerable to SQL injection. Exploitation requires having the system extension ext:lowlevel installed, and a valid backend user who has administrator privileges.

An issue was discovered in TYPO3 before 8.7.30, 9.x before 9.5.12, and 10.x before 10.2.2. It has been discovered that the extraction of manually uploaded ZIP archives in Extension Manager is vulnerable to directory traversal. Admin privileges are required in order to exploit this vulnerability. (In v9 LTS and later, System Maintainer privileges are also required.)

TYPO3 is an open source web content management system. Prior to versions 9.5.34 ELTS, 10.4.29, and 11.5.11, Admin Tool sessions initiated via the TYPO3 backend user interface had not been revoked even if the corresponding user account was degraded to lower permissions or disabled completely. This way, sessions in the admin tool theoretically could have been prolonged without any limit. TYPO3 versions 9.5.34 ELTS, 10.4.29, and 11.5.11 contain a fix for the problem.

### Meta CVSS: AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N/E:F/RL:O/RC:C (4.9)

Problem It has been discovered that user credentials have been logged as plaintext when explicitly using log level debug, which is not the default configuration.

Solution Update to TYPO3 versions 7.6.52 ELTS, 8.7.41 ELTS, 9.5.28, 10.4.18, 11.3.1 that fix the problem described.

Credits Thanks to Ingo Schmitt who reported this issue, and to TYPO3 core & security team member Benni Mack who fixed the issue.

References TYPO3-CORE-SA-2021-012

TYPO3 is an open source PHP based web content management system. In versions prior to 8.7.49, 9.5.38, 10.4.33, 11.5.20, and 12.1.1 TYPO3 is vulnerable to Improper Authentication. Restricting frontend login to specific users, organized in different storage folders (partitions), can be bypassed. A potential attacker might use this ambiguity in usernames to get access to a different account - however, credentials must be known to the adversary. This issue is patched in versions 8.7.49 ELTS, 9.5.38 ELTS, 10.4.33, 11.5.20, 12.1.1.

TYPO3 is an open source PHP based web content management system released under the GNU GPL. It has been discovered that the FileDumpController (backend and frontend context) is vulnerable to cross-site scripting when malicious files are displayed using this component. A valid backend user account is needed to exploit this vulnerability. Update to TYPO3 version 7.6.58 ELTS, 8.7.48 ELTS, 9.5.37 ELTS, 10.4.32 or 11.5.16 that fix the problem. There are no known workarounds for this issue.

### Meta CVSS: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N/E:F/RL:O/RC:C (4.9)

Problem It has been discovered that system internal credentials or keys (e.g. database credentials) have been logged as plaintext in exception handlers, when logging the complete exception stack trace.

Solution Update to TYPO3 versions 7.6.57 ELTS, 8.7.47 ELTS, 9.5.35 ELTS, 10.4.29, 11.5.11 that fix the problem described above.

Credits Thanks to Marco Huber who reported this issue and to TYPO3 security member Torben Hansen who fixed the issue.

References TYPO3-CORE-SA-2022-002

### Meta CVSS: CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N/E:F/RL:O/RC:C (4.5)

Problem Failing to properly encode error messages, the components QueryGenerator and QueryView are vulnerable to both reflected and persistent cross-site scripting. A valid backend user account having administrator privileges is needed to exploit this vulnerability.

Solution Update to TYPO3 versions 8.7.41 ELTS, 9.5.28, 10.4.18, 11.3.1 that fix the problem described.

Credits Thanks to Richie Lee who reported this issue and to TYPO3 security team member Oliver Hader who fixed the issue.

References TYPO3-CORE-SA-2021-010

Problem Failing to properly encode settings for backend layouts, the corresponding grid view is vulnerable to persistent cross-site scripting. A valid backend user account is needed to exploit this vulnerability.

Solution Update to TYPO3 versions 8.7.41 ELTS, 9.5.28, 10.4.18, 11.3.1 that fix the problem described.

Credits Thanks to TYPO3 core merger Oliver Bartsch who reported and fixed the issue.

### Meta CVSS: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N/E:F/RL:O/RC (5.0)

Problem Failing to properly encode Page TSconfig settings, corresponding page preview module (Web>View) is vulnerable to persistent cross-site scripting. A valid backend user account is needed to exploit this vulnerability.

Solution Update to TYPO3 versions 9.5.28, 10.4.18, 11.3.1 that fix the problem described.

Credits Thanks to TYPO3 core merger Oliver Bartsch who reported and fixed the issue.

References TYPO3-CORE-SA-2021-009

### Meta CVSS: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:F/RL:O/RC (5.7)

Problem Failing to properly parse, sanitize and encode malicious rich-text content, the content rendering process in the website frontend is vulnerable to cross-site scripting. Corresponding rendering instructions via TypoScript functionality HTMLparser do not consider all potentially malicious HTML tag & attribute combinations per default.

In addition, the lack of comprehensive default node configuration for rich-text fields in the backend user interface fosters this malfunction.

In default scenarios, a valid backend user account is needed to exploit this vulnerability. In case custom plugins used in the website frontend accept and reflect rich-text content submitted by users, no authentication is required.

Solution Update to TYPO3 versions 7.6.53 ELTS, 8.7.42 ELTS, 9.5.29, 10.4.19, 11.3.2 that fix the problem described above.

Custom package typo3/html-sanitizer - based on allow-lists only - takes care of sanitizing potentially malicious markup. The default behavior is based on safe and commonly used markup - however, this can be extended or restricted further in case it is necessary for individual scenarios.

During the frontend rendering process, sanitization is applied to the default TypoScript path lib.parseFunc, which is implicitly used by the Fluid view-helper instruction f:format.html. Rich-text data persisted using the backend user interface is sanitized as well. Implementation details are explained in corresponding ChangeLog documentation.

Credits Thanks to Benjamin Stiber, Gert-Jan Jansma, Gábor Ács-Kurucz, Alexander Kellner, Richie Lee, Nina Rösch who reported this issue, and to TYPO3 security team member Oliver Hader, as well as TYPO3 contributor Susanne Moog who fixed the issue.

References TYPO3-CORE-SA-2021-013

### Meta CVSS: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N/E:F/RL:O/RC:C (5.7) CWE-79

Problem It has been discovered that system extension Fluid (typo3/cms-fluid) of the TYPO3 core is vulnerable to cross-site scripting passing user-controlled data as argument to Fluid view helpers.

<f:form ... fieldNamePrefix="{payload}" /> <f:be.labels.csh ... label="{payload}" /> <f:be.menus.actionMenu ... label="{payload}" />

Solution Update to TYPO3 versions 9.5.23 or 10.4.10 that fix the problem described.

Credits Thanks to TYPO3 security team member Oliver Hader who reported this issue and to TYPO3 security team members Helmut Hummel & Oliver Hader who fixed the issue.

References TYPO3-CORE-SA-2020-010

Problem It has been discovered that Login Handling is susceptible to open redirection which allows attackers redirecting to arbitrary content, and conducting phishing attacks. No authentication is required in order to exploit this vulnerability.

Solution Update to TYPO3 versions 6.2.57, 7.6.51, 8.7.40, 9.5.25, 10.4.14, 11.1.1 that fix the problem described.

Credits Thanks to Alexander Kellner who reported this issue and to TYPO3 security team member Torben Hansen who fixed the issue.

References TYPO3-CORE-SA-2021-001

Cross-Site Scripting in Link Handling