Dompdf up to 3.15 CSS @font-face directive _dompdf_show_warnings information disclosure

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Dompdf up to 3.15. This affects an unknown part of the component CSS @font-face directive. Performing a manipulation of the argument _dompdf_show_warnings results in information disclosure. This vulnerability is cataloged as CVE-2026-55555. It is possible to initiate the attack remotely. There is no exploit available.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Dompdf up to 3.15. This affects an unknown functionality of the component CSS @font-face directive. The manipulation of the argument _dompdf_show_warnings with an unknown input leads to a information disclosure vulnerability. CWE is classifying the issue as CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. This is going to have an impact on confidentiality. The summary by CVE is:

Dompdf is an HTML to PDF converter for PHP. Versions 3.15 and prior are vulnerable to a File Existence Oracle attack through the manipulation of the CSS @font-face directive. By providing malicious HTML that references local files via the file:// protocol repeatedly, an attacker can trigger PHP memory exhaustion. Because Dompdf behaves differently depending on whether a referenced local file exists (an existing file is processed repeatedly until it triggers an "Allowed memory size exhausted" crash, whereas a missing file fails fast or is ignored and never hits the memory limit), an attacker can use this observable discrepancy as an oracle to enumerate sensitive files on the server regardless of CHROOT restrictions. Exploitation requires the attacker to supply unrestricted or unsanitized HTML in a request that permits large data, plus a configuration where Dompdf's memory limit is low enough to be exhausted (with  $_dompdf_show_warnings=true  making the overflow easier to reach). This issue has been fixed in version 3.16.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-55555 since 06/17/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1592 according to MITRE ATT&CK.

Upgrading to version 3.16 eliminates this vulnerability.

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Productinfo

Name

• Dompdf

Version

• 3.0
• 3.1
• 3.2
• 3.3
• 3.4
• 3.5
• 3.6
• 3.7
• 3.8
• 3.9
• 3.10
• 3.11
• 3.12
• 3.13
• 3.14
• 3.15

Website

• Product: https://github.com/dompdf/dompdf/

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