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Server-Side Request Forgery (SSRF)Weakness · CWE-918

CVE-2026-3958

MEDIUM · 6.3 CVSS v3.1 Published 2026-03-11
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
69/100
Remediation priority · Elevated
Remotely reachable Zero-click

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
A vulnerability has been found in Woahai321 ListSync up to 0.6.6. This issue affects the function requests.post of the file list-sync-main/api_server.py of the component JSON Handler. The manipulation leads to server-side request forgery. The attack is possible to be carried out remotely. The exploit has been disclosed to the public and may be used. The project was informed of the problem early through an issue report but has not responded yet.

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

Woahai321 ListSync up to version 0.6.6 contains a Server-Side Request Forgery (SSRF) vulnerability in the JSON Handler component of api_server.py. The vulnerability exists in the requests.post function call which does not properly validate user-controlled input before making HTTP requests, allowing an attacker to cause the server to make requests to arbitrary URLs.

MitigationImplement strict URL allowlist validation and input sanitization for all URLs passed to requests.post, ensuring only trusted/internal endpoints can be accessed. Additionally, restrict outbound network connections to prevent the server from reaching internal infrastructure.

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

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
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
Low

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

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. Identify if Woahai321 ListSync is installed
    Search for the application in your system using: find / -name 'listsync' -o -name 'ListSync' 2>/dev/null or check running processes for 'ListSync' or 'listsync'
    Affected if The application is present on the system
  2. Determine the installed version
    Check the version of ListSync by reviewing the source code, package.json, setup.py, or running: listsync --version or python -c "import listsync; print(listsync.__version__)" if available
    Affected if Version is 0.6.6 or lower (any version up to and including 0.6.6)
  3. Locate the api_server.py file
    Search for api_server.py in the application directory: find /path/to/listsync -name 'api_server.py' or ls -la <application_path>/api_server.py
    Affected if The api_server.py file exists in the installation
  4. Verify the JSON Handler endpoint is exposed
    Check if the API server is running and the JSON Handler endpoint is accessible. Review the api_server.py code to identify the route handling JSON input, typically endpoints like /json, /api/json, or similar
    Affected if The API server is running and the JSON Handler endpoint is accessible to users or attackers
  5. Confirm requests.post usage in JSON Handler
    Review the api_server.py source code and locate the requests.post function call within the JSON Handler component. Check if URL parameters are passed directly from user input without validation
    Affected if The code contains requests.post calls that accept user-supplied URLs without validation

You are affected if Woahai321 ListSync version 0.6.6 or lower is installed, the api_server.py component is running, and the JSON Handler endpoint is exposed with unvalidated URL input to requests.post.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement strict URL allowlist validation and input sanitization for all URLs passed to requests.post, ensuring only trusted/internal endpoints can be accessed. Additionally, restrict outbound network connections to prevent the server from reaching internal infrastructure.

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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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-2026-3958 in production — separate from our analysis above.

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