Summary
Field injection in the KirbyData text storage handler
TL;DR
This vulnerability affects all Kirby sites that might have potential attackers in the group of authenticated Panel users or that allow external visitors to update a Kirby content file (e.g. via a contact or comment form).
Your Kirby sites are not affected if they don't allow write access for untrusted users or visitors.
Introduction
A field injection in a content storage implementation is a type of vulnerability that allows attackers with content write access to overwrite content fields that the site developer didn't intend to be modified.
In a Kirby site this can be used to alter site content, break site behavior or inject malicious data or code. The exact security risk depends on the field type and usage.
Credits
Thanks to Patrick Falb (@dapatrese) at FORMER 03 for responsibly reporting the identified issue.
Impact
Kirby stores content of the site, of pages, files and users in text files by default. The text files use Kirby's KirbyData format where each field is separated by newlines and a line with four dashes (----).
When reading a KirbyData file, the affected code first removed the Unicode BOM sequence from the file contents and afterwards split the content into fields by the field separator.
When writing to a KirbyData file, field separators in field data are escaped to prevent user input from interfering with the field structure. However this escaping could be tricked by including a Unicode BOM sequence in a field separator (e.g. --\xEF\xBB\xBF--). When writing, this was not detected as a separator, but during the read process the BOM was removed, turning the malicious line into a valid separator. This could be abused by attackers to inject other field data into content files.
Because each field can only be defined once per content file, this vulnerability only affects fields in the content file that were defined above the vulnerable user-writable field or not at all. Fields that are defined below the vulnerable field override the injected field content and were therefore already protected.
The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions. Typical impact: unauthorized data access or execution of privileged operations.
CVE-2023-38488 has a CVSS score of 7.1 (High). The vector is network-reachable, low 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 (3.5.8.3, 3.6.6.3, 3.7.5.2, 3.8.4.1, 3.9.6); 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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The problem has been patched in Kirby 3.5.8.3, Kirby 3.6.6.3, Kirby 3.7.5.2, Kirby 3.8.4.1 and Kirby 3.9.6. Please update to one of these or a later version to fix the vulnerability.
In all of the mentioned releases, we have fixed the affected code to only remove the Unicode BOM sequence at the beginning of the file. This fixes this vulnerability both for newly written as well as for existing content files.
Frequently Asked Questions
- What is CVE-2023-38488? CVE-2023-38488 is a high-severity incorrect authorization vulnerability in getkirby/cms (composer), affecting versions < 3.5.8.3. It is fixed in 3.5.8.3, 3.6.6.3, 3.7.5.2, 3.8.4.1, 3.9.6. The application does not correctly enforce access controls, allowing a principal to access resources or operations beyond their granted permissions.
- How severe is CVE-2023-38488? CVE-2023-38488 has a CVSS score of 7.1 (High). 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-2023-38488? getkirby/cms (composer) versions < 3.5.8.3 is affected.
- Is there a fix for CVE-2023-38488? Yes. CVE-2023-38488 is fixed in 3.5.8.3, 3.6.6.3, 3.7.5.2, 3.8.4.1, 3.9.6. Upgrade to this version or later.
- Is CVE-2023-38488 exploitable, and should I be worried? Whether CVE-2023-38488 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-2023-38488 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-2023-38488?
- Upgrade
getkirby/cmsto 3.5.8.3 or later - Upgrade
getkirby/cmsto 3.6.6.3 or later - Upgrade
getkirby/cmsto 3.7.5.2 or later - Upgrade
getkirby/cmsto 3.8.4.1 or later - Upgrade
getkirby/cmsto 3.9.6 or later
- Upgrade