Summary
EZsystems Remote code execution in file uploads
This Security Advisory is about a vulnerability in the way eZ Platform and eZ Publish Legacy handles file uploads, which can in the worst case lead to remote code execution (RCE), a very serious threat. An attacker would need access to uploading files to be able to exploit the vulnerability, so if you have strict controls on this and trust all who have this permission, you're not affected. On the basis of the tests we have made, we also believe the vulnerability cannot be exploited as long as our recommended vhost configuration is used. Here is the v2.5 recommendation for Nginx, as an example:
https://github.com/ezsystems/ezplatform/blob/2.5/doc/nginx/vhost.template#L31
This vhost template specifies that only the file app.php in the web root is executed, while vulnerable configurations allow execution of any php file. Apache is affected in the same way as Nginx, and is also protected by using the recommended configuration. The build-in webserver in PHP stays vulnerable, as it doesn't use this type of configuration (this webserver should only be used for development, never for production). We cannot be 100% certain our configuration is not vulnerable. We also do not know if all our users use the recommended configuration, so we send out this fix to be on the safe side.
The fix includes a blacklist feature for uploaded filenames, such as ".php". The file types on the blacklist cannot be uploaded. The blacklist is configurable. In eZ Platform you will find it as ezsettings.default.io.file_storage.file_type_blacklist in eZ/Bundle/EzPublishCoreBundle/Resources/config/default_settings.yml in vendors/ezsystems/ezpublish-kernel. In eZ Publish Legacy you will find it as FileExtensionBlackList in settings/file.ini. By default it blocks these file types: php, php3, phar, phpt, pht, phtml, pgif. The fix also inclues a new block against path traversal attacks, though this kind of attack was not reproducible in our tests.
Impact
Untrusted input is evaluated as executable code within the application's runtime environment. Typical impact: arbitrary code execution within the application's privilege context.
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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ezsystems/ezpublish-legacy to 2019.3.4.2 or later; ezsystems/ezpublish-legacy to 2017.12.7.2 or later; ezsystems/ezpublish-legacy to 5.4.14.1 or later
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Frequently Asked Questions
- What is GHSA-9895-26WR-4FGV? GHSA-9895-26WR-4FGV is a high-severity code injection vulnerability in ezsystems/ezpublish-legacy (composer), affecting versions >= 2019.3.0, < 2019.3.4.2. It is fixed in 2019.3.4.2, 2017.12.7.2, 5.4.14.1. Untrusted input is evaluated as executable code within the application's runtime environment.
- Which versions of ezsystems/ezpublish-legacy are affected by GHSA-9895-26WR-4FGV? ezsystems/ezpublish-legacy (composer) versions >= 2019.3.0, < 2019.3.4.2 is affected.
- Is there a fix for GHSA-9895-26WR-4FGV? Yes. GHSA-9895-26WR-4FGV is fixed in 2019.3.4.2, 2017.12.7.2, 5.4.14.1. Upgrade to this version or later.
- Is GHSA-9895-26WR-4FGV exploitable, and should I be worried? Whether GHSA-9895-26WR-4FGV 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 GHSA-9895-26WR-4FGV 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 GHSA-9895-26WR-4FGV?
- Upgrade
ezsystems/ezpublish-legacyto 2019.3.4.2 or later - Upgrade
ezsystems/ezpublish-legacyto 2017.12.7.2 or later - Upgrade
ezsystems/ezpublish-legacyto 5.4.14.1 or later
- Upgrade