CVE-2025-27607

HIGH 8.8CVE-2025-27607 · Published 07/03/2025 · updated 17/06/2026

In short

CVE-2025-27607 is a HIGH (CVSS 8.8) vulnerability affecting python json logger (nhairs).
Chance of exploitation in the next 30 days (EPSS): 1.6%, higher than 76.1% of all vulnerabilities.
Fix: update to 3.3.0 or later.

Package	Affected versions	Patched versions
python json logger nhairs	`< 3.3.0`	`3.3.0`

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.

References

nhairs/python-json-logger commit 2548e3a · Patch
nhairs/python-json-logger commit e7761e5 · Patch
nhairs/python-json-logger security advisory · Exploit

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