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Fencer Vulns
high 8.8

CVE-2025-27607 json

Python JSON Logger has a Potential RCE via missing `msgspec-python313-pre` dependency

published 2025-03-07 20 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-7799

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.6%
EPSS 1.6% chance of exploitation in 30 days, percentile 76%
public exploits
0
none known

Summary

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.

Patch / fix

  • nhairs python_json_logger 3.3.0

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-27607 updated cvss 8.8

python-json-logger: Python JSON Logger has a Potential RCE via missing `msgspec-python313-pre` dependency

  • Red Hat OpenStack Platform 16.2 python3-json-logger Red Hat OpenStack Platform 17.1 python3-json-logger
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
20 mo ago

Exploit prediction

1.61% chance of exploitation in the next 30 days, higher than 76% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/nhairs/python-json-logger/security/advisories/GHSA-wmxh-pxcx-9w24 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected products

  • nhairs python-json-logger

Classification

Weakness
  • CWE-829 Inclusion of Functionality from Untrusted Control Sphere

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.