Dompdf: File existence oracle via font-face stylesheet declaration

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-55555
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-28 20:17:26 UTC
Updated2026-07-30 16:33:59 UTC
DescriptionDompdf 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.

Risk And Classification

Primary CVSS: v4.0 2.3 LOW from [email protected]

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

EPSS: 0.005040000 probability, percentile 0.403020000 (date 2026-07-31)

Problem Types: CWE-203 | CWE-203 CWE-203: Observable Discrepancy

VersionSourceTypeScoreSeverityVector
4.0[email protected]Secondary2.3LOWCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/C...
4.0CNADECLARED2.3LOWCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

CVSS v4.0 Breakdown

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
Present
Privileges Required
None
User Interaction
Passive
Confidentiality
Low
Integrity
None
Availability
None
Sub Conf.
None
Sub Integrity
None
Sub Availability
None

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Dompdf Dompdf affected < 3.1.6 Not specified

References

ReferenceSourceLinkTags
github.com/dompdf/dompdf/security/advisories/GHSA-7x2p-4jvh-6384 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
github.com/dompdf/dompdf/releases/tag/v3.1.6 [email protected] github.com
github.com/dompdf/dompdf/commit/75c39a083bf7298044fb27399b4cc183054438b4 [email protected] github.com
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