dbcve.org
Deserialization of Untrusted DataWeakness · CWE-502

CVE-2025-50460

CRITICAL · 9.8 CVSS v3.1 Published 2025-08-01
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges 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 remote code execution (RCE) vulnerability exists in the ms-swift project version 3.3.0 due to unsafe deserialization in tests/run.py using yaml.load() from the PyYAML library (versions = 5.3.1). If an attacker can control the content of the YAML configuration file passed to the --run_config parameter, arbitrary code can be executed during deserialization. This can lead to full system compromise. The vulnerability is triggered when a malicious YAML file is loaded, allowing the execution of arbitrary Python commands such as os.system(). It is recommended to upgrade PyYAML to version 5.4 or higher, and to use yaml.safe_load() to mitigate the issue.

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 · high confidence

The ms-swift project version 3.3.0 contains an unsafe deserialization vulnerability in tests/run.py where yaml.load() from PyYAML (version 5.3.1) is used to parse configuration files passed via the --run_config parameter. Attackers can craft malicious YAML files containing Python object payloads that execute arbitrary commands (e.g., os.system()) during deserialization, leading to full system compromise.

MitigationUpgrade PyYAML to version 5.4 or higher and refactor the codebase to use yaml.safe_load() instead of yaml.load() to prevent arbitrary code execution through deserialization attacks.

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
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. Identify ms-swift installation and version
    Run 'pip show ms-swift' or check the installed package metadata to confirm version 3.3.0 is present
    Affected if ms-swift version 3.3.0 is installed
  2. Locate tests/run.py and inspect for yaml.load usage
    Find the tests/run.py file in the ms-swift installation directory and search for 'yaml.load(' calls, particularly those processing the --run_config parameter
    Affected if tests/run.py exists and contains yaml.load() being used to parse the --run_config parameter
  3. Determine installed PyYAML version
    Run 'pip show PyYAML' to check the installed version number
    Affected if PyYAML version is below 5.4 (e.g., 5.3.x or earlier)
  4. Check for usage of --run_config with untrusted YAML files
    Review how the --run_config parameter is invoked in your environment - examine command lines, scripts, or automation that pass YAML files to tests/run.py
    Affected if The --run_config parameter is used to load YAML configuration files from untrusted or user-controlled sources

You are affected if you have ms-swift version 3.3.0 with tests/run.py using yaml.load() on the --run_config parameter while running PyYAML version below 5.4, and you process untrusted YAML files through this code path.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade PyYAML to version 5.4 or higher and refactor the codebase to use yaml.safe_load() instead of yaml.load() to prevent arbitrary code execution through deserialization attacks.

Recommended fix High confidence
  1. 1. Locate the vulnerable file tests/run.py in the ms-swift project
  2. 2. Find the line(s) that use yaml.load() without a safe Loader argument
  3. 3. Replace yaml.load() with yaml.safe_load() to prevent arbitrary code execution
  4. 4. If yaml.load() with a specific Loader is required, use yaml.safe_load() or yaml.load(data, Loader=yaml.SafeLoader) instead
  5. 5. Verify the fix by testing with a benign YAML configuration file
  6. 6. Ensure PyYAML is upgraded to version 5.4 or higher as an additional defense-in-depth measure
Caveat Using yaml.safe_load() will reject Python-specific YAML tags (!python/object, !python/module, etc.); review config files to ensure they don't rely on these tags

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

Have this fixed Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,240
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,984.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2025-50460 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2025-50460 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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