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

Exp

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.

Published: 2025-03-07 Last update: 2025-07-01 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-27607 is rated High Exploit Risk (88.7/100): CVSS High severity, with high exploitation likelihood (EPSS 21.76%, 96th percentile). 1 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +12.47% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2025-27607

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2025-27607

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-15 9.30% 21.76% +12.47%
2 2026-01-01 8.05% 9.30% +1.24%
3 2025-12-22 — 8.05% —

Full EPSS history (29 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-27607

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
8.8 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.8 5.9 [email protected]

Weakness enumeration for CVE-2025-27607

OS Trackers for CVE-2025-27607

vendor priority summary link
debian unimportant CVE-2025-27607 unimportant priority: Debian including 1 source packages (python-pythonjsonlogger), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2025-27607
redhat high — https://access.redhat.com/security/cve/CVE-2025-27607
suse high — https://www.suse.com/security/cve/CVE-2025-27607/
ubuntu medium CVE-2025-27607 medium priority: Ubuntu including 1 source packages (python-pythonjsonlogger), 7 status rows across 7 suites (focal, jammy, noble, oracular, plucky, questing, upstream): needs-triage 5, ignored 2. https://ubuntu.com/security/CVE-2025-27607

Affected software / configurations for CVE-2025-27607

Vendor Product Version Raw CPE
nhairs python_json_logger < 3.3.0 cpe:2.3:a:nhairs:python_json_logger:*:*:*:*:*:*:*:*

References for CVE-2025-27607

cvelogic Threat Intelligence