CVE-2025-55161: Stirling-PDF SSRF vulnerability on /api/v1/convert/markdown/pdf

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.1% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2025-08-11 · updated 2026-06-17
Weakness: CWE-918

Description

Stirling-PDF is a locally hosted web application that performs various operations on PDF files. Prior to version 1.1.0, when using the /api/v1/convert/markdown/pdf endpoint to convert Markdown to PDF, the backend calls a third-party tool to process it and includes a sanitizer for security sanitization which can be bypassed and result in SSRF. This issue has been patched in version 1.1.0.

Affected products

Stirling-Tools Stirling-PDF: before 1.1.0 — fixed in 1.1.0

How to fix

Upgrade to a fixed version: Stirling-Tools Stirling-PDF 1.1.0. Check the vendor advisory for mitigations.

References

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