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Stirling PdfApplication · Stirlingpdf

CVE-2025-55161

CRITICAL · 9.8 CVSS v3.1 Published 2025-08-11
Fix available
A fix is available. Upgrade to 1.1.0 or later.
See remediation →
100/100
Remediation priority · Urgent
Public exploit Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · moderate confidence

Stirling-PDF versions prior to 1.1.0 contain an SSRF vulnerability in the /api/v1/convert/markdown/pdf endpoint. The backend invokes a third-party tool to process Markdown-to-PDF conversions and includes a security sanitizer, but this sanitizer can be bypassed, allowing attackers to make the server perform arbitrary requests to internal or external resources.

MitigationUpgrade to Stirling-PDF version 1.1.0 or later. If immediate patching is not possible, restrict network access to the application and consider disabling the markdown-to-PDF conversion functionality as a temporary workaround.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Stirling PdfApplication
Affected:< 1.1.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Confirm Stirling-PDF is running
    Identify if the Stirling-PDF application is running in your environment by checking running processes, docker containers, or accessible web services (commonly on ports 8080, 80, or 443). Look for the application's web interface in your browser or via network scanning.
    Affected if Stirling-PDF is found running in your environment
  2. Determine the installed version
    Check the installed version by accessing the application's Settings or About page in the web UI, or by inspecting the docker image tag, build configuration, or version file if you deployed manually.
    Affected if The version is less than 1.1.0 (any version prior to 1.1.0)
  3. Verify the markdown-to-PDF conversion feature is available
    Check if the /api/v1/convert/markdown/pdf endpoint is accessible in your instance by reviewing the application's available conversion options in the UI or attempting to access the endpoint directly via HTTP request.
    Affected if The markdown-to-PDF conversion functionality is present and the endpoint responds to requests
  4. Check network accessibility of the server
    Determine if the server hosting Stirling-PDF has the ability to make outbound HTTP/HTTPS requests to other internal or external resources, as this is required for the SSRF vulnerability to be exploitable.
    Affected if The Stirling-PDF server can initiate outbound network connections

You are affected if Stirling-PDF version less than 1.1.0 is running with the markdown-to-PDF conversion feature enabled and the server has network access.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.1.0 or later
Fixed in 1.1.0
Vendor patch github.com →
Interim mitigation

Upgrade to Stirling-PDF version 1.1.0 or later. If immediate patching is not possible, restrict network access to the application and consider disabling the markdown-to-PDF conversion functionality as a temporary workaround.

Recommended fix High confidence

version 1.1.0

  1. 1. Back up your current Stirling-PDF installation and configuration files.
  2. 2. Download version 1.1.0 of Stirling-PDF from the official GitHub repository (https://github.com/Stirling-Tools/Stirling-PDF/releases/tag/1.1.0).
  3. 3. Stop the running Stirling-PDF service.
  4. 4. Replace the existing installation with the new version 1.1.0 files.
  5. 5. Restore your backed-up configuration files to the new installation.
  6. 6. Start the Stirling-PDF service and verify it is running correctly.
  7. 7. Test the /api/v1/convert/markdown/pdf endpoint to confirm the SSRF vulnerability is patched.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Stirling Pdf Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing4.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,360
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2025-55161 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data