CVE-2026-55555 Dompdf Project CVE debrief

Who should care

Developers and administrators using Dompdf versions 3.15 or earlier should update to version 3.16 or later to mitigate this vulnerability. Additionally, security teams and vulnerability management teams should review the affected scope and assess their exposure to this vulnerability. Operators of platforms using Dompdf should also be aware of the potential impact and take necessary precautions.

Technical summary

Dompdf versions 3.15 and prior are vulnerable to a File Existence Oracle attack through manipulation of the CSS @font-face directive. This allows attackers to enumerate sensitive files on the server by providing malicious HTML that references local files via the file:// protocol repeatedly, potentially leading to PHP memory exhaustion. The vulnerability can be exploited when an attacker supplies unrestricted or unsanitized HTML in a request that permits large data, and the configuration has a low memory limit for Dompdf.

Defensive priority

Low-priority defensive actions recommended due to low CVSS score of 2.3.

Recommended defensive actions

• Update Dompdf to version 3.16 or later
• Restrict HTML input to prevent malicious file references
• Monitor for suspicious memory exhaustion errors
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

Evidence from official CVE and NVD sources indicates Dompdf versions 3.15 and prior are vulnerable to a File Existence Oracle attack through manipulation of the CSS @font-face directive. Limited details on exploitation and affected scope are provided. Further verification is needed to determine the full impact and to confirm affected deployments. Defenders should review official advisories and monitor for suspicious memory exhaustion errors.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.