# CVE-2026-55555: Dompdf file existence oracle in CSS @font-face directive

Source: https://junglewise.ai/threats/cve-2026-55555-dompdf-file-existence-oracle-in-css-font-face-directive  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-28. Updated: 2026-07-28  
License: CC BY 4.0 with a link back

CVE-2026-55555 · Severity: medium · CVSS 4 · Published 2026-07-28

Dompdf is a PHP library used to convert HTML documents into PDF files. A security flaw allows an attacker to determine if specific sensitive files exist on the server by sending specially crafted HTML that triggers a memory crash only when a file is present. This can be used to map out a server's internal file structure or confirm the presence of configuration files and security keys, potentially aiding further attacks.

Technologies: [Dompdf](https://junglewise.ai/threats/technologies/dompdf), [dompdf/dompdf (Packagist)](https://junglewise.ai/threats/technologies/dompdf-dompdf). Vendors: [Dompdf](https://junglewise.ai/threats/vendors/dompdf), [Packagist](https://junglewise.ai/threats/vendors/packagist).

## Quick answers

**Is CVE-2026-55555 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-55555 being exploited in the wild.

**How severe is CVE-2026-55555?** Medium severity, with a CVSS score of 4, published 28 July 2026.

**Which products and versions are affected?** Dompdf < 3.1.6, <= 3.1.5; dompdf/dompdf (Packagist) < 3.1.6, ECOSYSTEM:introduced=0,fixed=3.1.6.

**Is there a fix for CVE-2026-55555?** Yes. dompdf/dompdf (Packagist): upgrade to 3.1.6 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-55555 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-55555?** Check whether you run Dompdf or dompdf/dompdf (Packagist) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- dompdf/dompdf (Packagist): upgrade to 3.1.6 or later

  ```sh
  composer require dompdf/dompdf:^3.1.6
  ```


## Technical details

Dompdf (versions 3.1.5 and prior) is 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. The vulnerability stems from an observable discrepancy: if a referenced local file exists, Dompdf attempts to process the resource multiple times until it hits the 'Allowed memory size exhausted' limit; if the file does not exist, it fails fast without exhausting memory. This allows an attacker to bypass CHROOT restrictions to enumerate sensitive files. Exploitation requires the ability to submit unsanitized HTML to an endpoint with a low enough PHP memory limit to be triggered. The issue is fixed in version 3.1.6.

## Affected products

- dompdf dompdf <= 3.1.5

## Identifiers

- CVE-2026-55555
- GHSA-7x2p-4jvh-6384

## Timeline

- 2026-07-20: patched: Fixed in version 3.1.6
- 2026-07-20: advisory: GitHub Security Advisory GHSA-7x2p-4jvh-6384 published
- 2026-07-28: disclosed: CVE-2026-55555 published to NVD

## References

- [https://github.com/dompdf/dompdf/commit/75c39a083bf7298044fb27399b4cc183054438b4](https://github.com/dompdf/dompdf/commit/75c39a083bf7298044fb27399b4cc183054438b4)
- [https://github.com/dompdf/dompdf/releases/tag/v3.1.6](https://github.com/dompdf/dompdf/releases/tag/v3.1.6)
- [https://github.com/dompdf/dompdf/security/advisories/GHSA-7x2p-4jvh-6384](https://github.com/dompdf/dompdf/security/advisories/GHSA-7x2p-4jvh-6384)

## Related threats

- [Dompdf information disclosure via SVG image references](https://junglewise.ai/threats/cve-2026-59943-dompdf-information-disclosure-via-svg-image-references)
- [Dompdf resource exhaustion Denial of Service via oversized images](https://junglewise.ai/threats/cve-2026-59942-dompdf-resource-exhaustion-denial-of-service-via-oversized-images)
- [Dompdf uncontrolled resource consumption in BMP processing](https://junglewise.ai/threats/cve-2026-59941-dompdf-uncontrolled-resource-consumption-in-bmp-processing)
- [Dompdf local file read via SVG data-URI bypass](https://junglewise.ai/threats/cve-2026-56722-dompdf-local-file-read-via-svg-data-uri-bypass)
- [Dompdf chroot validation bypass in validateLocalUri](https://junglewise.ai/threats/cve-2026-55554-dompdf-chroot-validation-bypass-in-validatelocaluri)