Summary
Strapi plugins vulnerable to Server-Side Template Injection and Remote Code Execution in the Users-Permissions Plugin
Strapi through 4.5.5 allows authenticated Server-Side Template Injection (SSTI) that can be exploited to execute arbitrary code on the server.
Details
Strapi through 4.5.5 allows authenticated Server-Side Template Injection (SSTI) that can be exploited to execute arbitrary code on the server. A remote attacker with access to the Strapi admin panel can inject a crafted payload that executes code on the server into an email template that bypasses the validation checks that should prevent code execution.
IoC
Using just the request log files, the only IoC to search for is a PUT request to URL path /users-permissions/email-templates. This IoC only indicates that a Strapi email template was modified on your server and by itself does not indicate if your Strapi server has been compromised. If this IoC is detected, you will need to manually review your email templates on your Strapi server and backups of your database to see if any of the templates contain a lodash template delimiter (eg. <%STUFF HERE%>) that contains suspicious JavaScript code. Generally speaking these templates should look like the following, you may have minor adjustments but any unrecognized code should be considered suspicious.
Reset Password Template:
<p>We heard that you lost your password. Sorry about that!</p>
<p>But don’t worry! You can use the following link to reset your password:</p>
<p><%= URL %>?code=<%= TOKEN %></p>
<p>Thanks.</p>
Email Confirmation Template:
<p>Thank you for registering!</p>
<p>You have to confirm your email address. Please click on the link below.</p>
<p><%= URL %>?confirmation=<%= CODE %></p>
<p>Thanks.</p>
Specifically you should look for odd code contained within the <%STUFF HERE%> blocks as this is what is used to bypass the lodash templating system. If you find any code that is not a variable name, or a variable name that is not defined in the template you are most likely impacted and should take immediate steps to confirm there are no malicious applications running on your servers.
Impact
All users on Strapi below 4.5.6 with access to the admin panel and the ability to modify the email templates
CVE-2023-22621 has a CVSS score of 10.0 (Critical). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (4.5.6); upgrading removes the vulnerable code path.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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@strapi/plugin-users-permissions to 4.5.6 or later; @strapi/plugin-email to 4.5.6 or later
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2023-22621? CVE-2023-22621 is a critical-severity security vulnerability in @strapi/plugin-users-permissions (npm), affecting versions < 4.5.6. It is fixed in 4.5.6.
- How severe is CVE-2023-22621? CVE-2023-22621 has a CVSS score of 10.0 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which packages are affected by CVE-2023-22621?
@strapi/plugin-users-permissions(npm) (versions < 4.5.6)@strapi/plugin-email(npm) (versions < 4.5.6)
- Is there a fix for CVE-2023-22621? Yes. CVE-2023-22621 is fixed in 4.5.6. Upgrade to this version or later.
- Is CVE-2023-22621 exploitable, and should I be worried? Whether CVE-2023-22621 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2023-22621 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2023-22621?
- Upgrade
@strapi/plugin-users-permissionsto 4.5.6 or later - Upgrade
@strapi/plugin-emailto 4.5.6 or later
- Upgrade