What’s Vulnerable › Vulnerabilities

CVE-2025-27607: Python JSON Logger has a Potential RCE via missing `msgspec-python313-pre` dependency

• Severity: high (CVSS 8.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.6% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2025-03-07 · updated 2026-06-17
• Weakness: CWE-829

Description

Python JSON Logger is a JSON Formatter for Python Logging. Between 30 December 2024 and 4 March 2025 Python JSON Logger was vulnerable to RCE through a missing dependency. This occurred because msgspec-python313-pre was deleted by the owner leaving the name open to being claimed by a third party. If the package was claimed, it would allow them RCE on any Python JSON Logger user who installed the development dependencies on Python 3.13 (e.g. pip install python-json-logger[dev]). This issue has been resolved with 3.3.0.

Affected products

• nhairs python-json-logger: before 3.3.0 — fixed in 3.3.0

How to fix

Upgrade to a fixed version: nhairs python-json-logger 3.3.0. Check the vendor advisory for mitigations.

References

• https://github.com/nhairs/python-json-logger/commit/2548e3a2e3cedf6bef3ee7c60c55b7c02d1af11a
• https://github.com/nhairs/python-json-logger/commit/e7761e56edb980cfab0165e32469d5fd017a5d72
• https://github.com/nhairs/python-json-logger/security/advisories/GHSA-wmxh-pxcx-9w24
• https://github.com/nhairs/python-json-logger/security/advisories/GHSA-wmxh-pxcx-9w24

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