CVE-2020-26255

Kirby Panel users could upload PHP Phar archives as content files before v2.5.14 and v3.4.5

Workarounds

Kirby 2 sites on older releases can also be patched by applying the changes from this commit.

Credits

Thanks to Thore Imhof of Accenture for reporting the problem.

An editor with full access to the Kirby Panel can upload a PHP .phar file and execute it on the server. This vulnerability is critical if you might have potential attackers in your group of authenticated Panel users, as they can gain access to the server with such a Phar file.

Visitors without Panel access cannot use this attack vector.

The application accepts file uploads without adequately restricting the file type or content. Typical impact: remote code execution if the uploaded file can be served and executed on the server.

CVE-2020-26255 has a CVSS score of 6.8 (Medium). The vector is network-reachable, high 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 (2.5.14, 3.4.5); upgrading removes the vulnerable code path.

Kodem intelligence

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The problem has been patched in Kirby 2.5.14 and Kirby 3.4.5. Please update to one of these or a later version to fix the vulnerability.

Note: Kirby 2 reaches end of life on December 31, 2020. We therefore recommend to upgrade your Kirby 2 sites to Kirby 3. If you cannot upgrade, we still recommend to update to Kirby 2.5.14.

1. What is CVE-2020-26255? CVE-2020-26255 is a medium-severity unrestricted upload of dangerous file types vulnerability in getkirby/panel (composer), affecting versions < 2.5.14. It is fixed in 2.5.14, 3.4.5. The application accepts file uploads without adequately restricting the file type or content.
2. How severe is CVE-2020-26255? CVE-2020-26255 has a CVSS score of 6.8 (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.
3. Which packages are affected by CVE-2020-26255?
   • getkirby/panel (composer) (versions < 2.5.14)
   • getkirby/cms (composer) (versions >= 3.0.0, < 3.4.5)
4. Is there a fix for CVE-2020-26255? Yes. CVE-2020-26255 is fixed in 2.5.14, 3.4.5. Upgrade to this version or later.
5. Is CVE-2020-26255 exploitable, and should I be worried? Whether CVE-2020-26255 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
6. What actually determines whether CVE-2020-26255 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.
7. How do I fix CVE-2020-26255?
   • Upgrade getkirby/panel to 2.5.14 or later
   • Upgrade getkirby/cms to 3.4.5 or later

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