Summary
Kirby vulnerable to unrestricted file upload of user avatar images
TL;DR
This vulnerability affects all Kirby sites that might have potential attackers in the group of authenticated Panel users.
The attack requires user interaction by another user or visitor and cannot be automated.
Introduction
Unrestricted upload of files with a dangerous type is a type of vulnerability that allows to circumvent expectations and protections in the server setup or backend code. Uploaded files are not checked for their compliance with the intended purpose of the upload target, which can introduce secondary attack vectors.
While the vulnerability described here does not allow critical attacks like remote code execution (RCE), it can still be abused to upload unexpected file types that could for example make it possible to perform cross-site scripting (XSS) attacks.
Credits
Thanks to Natwara Archeepsamooth (@PlyNatwara) for responsibly reporting the identified issue.
Impact
Users with Panel access can upload a user avatar in their own account view. This avatar is intended to be an image, however the file type or file extension was not validated on the backend. This effectively allowed to upload many types of files that would then be stored with the filename profile and the provided file extension.
While the upload is protected against dangerous file types such as HTML files or executable PHP files, this could be abused to upload unexpected files such as PDFs that would then be available via a direct link. These links could be shared to other users.
Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.
CVE-2024-26483 has a CVSS score of 4.6 (Medium). The vector is network-reachable, low privileges required, and user interaction required. 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 (3.6.6.5, 3.7.5.4, 3.8.4.3, 3.9.8.1, 3.10.0.1, 4.1.1); 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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The problem has been patched in Kirby 3.6.6.5, Kirby 3.7.5.4, Kirby 3.8.4.3, Kirby 3.9.8.1, Kirby 3.10.0.1, and Kirby 4.1.1. Please update to one of these or a later version to fix the vulnerability.
In all of the mentioned releases, we have added validations that prevent any files that don't have an image file extension or MIME type from being uploaded as a user avatar.
Frequently Asked Questions
- What is CVE-2024-26483? CVE-2024-26483 is a medium-severity cross-site scripting (XSS) vulnerability in getkirby/cms (composer), affecting versions <= 3.6.6.4. It is fixed in 3.6.6.5, 3.7.5.4, 3.8.4.3, 3.9.8.1, 3.10.0.1, 4.1.1. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
- How severe is CVE-2024-26483? CVE-2024-26483 has a CVSS score of 4.6 (Medium). 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 versions of getkirby/cms are affected by CVE-2024-26483? getkirby/cms (composer) versions <= 3.6.6.4 is affected.
- Is there a fix for CVE-2024-26483? Yes. CVE-2024-26483 is fixed in 3.6.6.5, 3.7.5.4, 3.8.4.3, 3.9.8.1, 3.10.0.1, 4.1.1. Upgrade to this version or later.
- Is CVE-2024-26483 exploitable, and should I be worried? Whether CVE-2024-26483 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-2024-26483 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-2024-26483?
- Upgrade
getkirby/cmsto 3.6.6.5 or later - Upgrade
getkirby/cmsto 3.7.5.4 or later - Upgrade
getkirby/cmsto 3.8.4.3 or later - Upgrade
getkirby/cmsto 3.9.8.1 or later - Upgrade
getkirby/cmsto 3.10.0.1 or later - Upgrade
getkirby/cmsto 4.1.1 or later
- Upgrade