GHSA-3x7x-943g-269w: Stirling-PDF: AI create-pdf-from-html-agent skips HTML sanitization enabling WeasyPrint SSRF and local file read
Stirling-PDF is a locally hosted web application that facilitates various operations on PDF files. Prior to 3.0.0, POST /api/v1/ai/tools/create-pdf-from-html-agent accepts attacker-controlled htmlContent and passes it to WeasyPrint without CustomHtmlSanitizer, unlike the sanitized /api/v1/convert/html/pdf control path. HTTP and HTTPS resource references can make server-side requests to internal or cloud-metadata destinations, while file references can embed local content readable by the Stirling-PDF process into the generated PDF. The endpoint is reachable without credentials when security.enableLogin is false, and the flaw is distinct from earlier Stirling-PDF WeasyPrint vulnerabilities in older conversion paths. This issue is fixed in version 3.0.0.
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
Stirling-PDFto a version that resolves this vulnerability.Fixed in 3.0.0 - Configuration
Enable login authentication so the endpoint is not reachable without credentials.
Stirling-PDF security.enableLogin = true
Event History
Frequently Asked Questions
Which deployments are most exposed?
Stirling-PDF deployments running versions before 3.0.0 are affected. The endpoint can be reached without credentials when security.enableLogin is false, making such deployments particularly exposed to unauthenticated requests.
What can an attacker access through this issue?
An attacker can supply HTML that causes WeasyPrint to request HTTP or HTTPS resources, including internal services or cloud metadata endpoints. File references can also place local files readable by the Stirling-PDF process into the generated PDF.
Is the normal HTML-to-PDF conversion endpoint affected in the same way?
The described issue is specific to POST /api/v1/ai/tools/create-pdf-from-html-agent, which does not apply CustomHtmlSanitizer. The /api/v1/convert/html/pdf path is identified as the sanitized control path.
What is the available remediation?
Upgrade Stirling-PDF to version 3.0.0, which fixes this issue.