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CRITICAL severity

CVE-2025-50460 — ms-swift

CRITICALFix: modelscope/ms-swift#5174

CVE-2025-50460 is a critical-severity (CVSS 9.8) remote code execution vulnerability in ms-swift. No vendor fix is recorded yet; mitigation options are listed below.

MS SWIFT Remote Code Execution via unsafe PyYAML deserialization

Also known asPYSEC-2026-1683
Published
Jul 31, 2025
Updated
Jul 7, 2026
Affected
1 pkg
Patched
See advisory
Exploits
None indexed
Exploitation data as of Sep 22, 2026 · OSV.dev, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-50460.

EPSS Exploitation Probability

via FIRST.org ↗
2.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs84th percentile — riskier than 84% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

How urgent is this, really

CVE-2025-50460 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.

Where this sits among everything scored

Of 377,636 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.

Real-World Exposure

1 pkg affected
🐍ms-swift

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Description

A Remote Code Execution (RCE) vulnerability exists in the modelscope/ms-swift project due to unsafe use of yaml.load() in combination with vulnerable versions of the PyYAML library (≤ 5.3.1). The issue resides in the tests/run.py script, where a user-supplied YAML configuration file is deserialized using yaml.load() with yaml.FullLoader.

If an attacker can control or replace the YAML configuration file provided to the --run_config argument, they may inject a malicious payload that results in arbitrary code execution.

Affected Repository

Vulnerable Code

if args.run_config is not None and Path(args.run_config).exists():
    with open(args.run_config, encoding='utf-8') as f:
        run_config = yaml.load(f, Loader=yaml.FullLoader)

Proof of Concept (PoC)

Step 1: Create malicious YAML file (exploit.yaml)

!!python/object/new:type
args: ["z", !!python/tuple [], {"extend": !!python/name:exec }]
listitems: "__import__('os').system('mkdir HACKED')"

Step 2: Execute with vulnerable PyYAML (<= 5.3.1)

import yaml

with open("exploit.yaml", "r") as f:
    cfg = yaml.load(f, Loader=yaml.FullLoader)

This results in execution of os.system, proving code execution.

Mitigation

  • Replace yaml.load() with yaml.safe_load()
  • Upgrade PyYAML to version 5.4 or later

Example Fix:

# Before
yaml.load(f, Loader=yaml.FullLoader)

# After
yaml.safe_load(f)

Author

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
🐍PyPIms-swiftall versionsNo fix

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ms-swift, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Remediation status

    No patched version of ms-swift has shipped for CVE-2025-50460 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.

  3. Mitigate without a patch

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-50460 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2025-50460. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

## Description A Remote Code Execution (RCE) vulnerability exists in the [modelscope/ms-swift](https://github.com/modelscope/ms-swift) project due to unsafe use of `yaml.load()` in combination with vulnerable versions of the PyYAML library (≤ 5.3.1). The issue resides in the `tests/run.py` script, where a user-supplied YAML configuration file is deserialized using `yaml.load()` with `yaml.FullLoader`. If an attacker can control or replace the YAML configuration file provided to the `--run_config` argument, they may inject a malicious payload that results in arbitrary code execution. ## Affe
O3 Security · Impact-Aware SCA

Is CVE-2025-50460 in your dependencies?

O3 Security finds CVE-2025-50460 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

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