CVE-2025-66034 Vulnerability Analysis & Exploit Details

CVE-2025-66034
Vulnerability Scoring

6.3
/10
High Risk

If left unpatched, CVE-2025-66034 could lead to major system disruptions or data loss.

Attack Complexity Details

  • Attack Complexity: High
    Exploits require significant effort and special conditions.
  • Attack Vector: Local
    Vulnerability requires local system access.
  • Privileges Required: None
    No privileges are required for exploitation.
  • Scope: Changed
    Successful exploitation can impact components beyond the vulnerable component.
  • User Interaction: Required
    User interaction is necessary for successful exploitation.

CVE-2025-66034 Details

Status: Analyzed

Last updated: 🕤 03 Dec 2025, 21:50 UTC
Originally published on: 🕐 29 Nov 2025, 01:16 UTC

Time between publication and last update: 4 days

CVSS Release: version 3

CVSS3 Source

security-advisories@github.com

CVSS3 Type

Secondary

CVSS3 Vector

CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:L

CVE-2025-66034 Vulnerability Summary

CVE-2025-66034: fontTools is a library for manipulating fonts, written in Python. In versions from 4.33.0 to before 4.60.2, the fonttools varLib (or python3 -m fontTools.varLib) script has an arbitrary file write vulnerability that leads to remote code execution when a malicious .designspace file is processed. The vulnerability affects the main() code path of fontTools.varLib, used by the fonttools varLib CLI and any code that invokes fontTools.varLib.main(). This issue has been patched in version 4.60.2.

Assessing the Risk of CVE-2025-66034

Access Complexity Graph

The exploitability of CVE-2025-66034 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2025-66034

CVE-2025-66034 presents a challenge to exploit due to its high attack complexity, but the absence of privilege requirements still makes it a viable target for skilled attackers. A thorough security review is advised.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2025-66034, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2025-66034, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2025-66034 has no significant impact on data confidentiality.
  • Integrity: High
    CVE-2025-66034 could allow unauthorized modifications to data, potentially affecting system reliability and trust.
  • Availability: Low
    CVE-2025-66034 may slightly degrade system performance without fully affecting service availability.

CVE-2025-66034 References

External References

CWE Common Weakness Enumeration

CWE-91

CAPEC Common Attack Pattern Enumeration and Classification

  • XML Injection CAPEC-250 An attacker utilizes crafted XML user-controllable input to probe, attack, and inject data into the XML database, using techniques similar to SQL injection. The user-controllable input can allow for unauthorized viewing of data, bypassing authentication or the front-end application for direct XML database access, and possibly altering database information.
  • XPath Injection CAPEC-83 An attacker can craft special user-controllable input consisting of XPath expressions to inject the XML database and bypass authentication or glean information that they normally would not be able to. XPath Injection enables an attacker to talk directly to the XML database, thus bypassing the application completely. XPath Injection results from the failure of an application to properly sanitize input used as part of dynamic XPath expressions used to query an XML database.

Vulnerable Configurations

  • cpe:2.3:a:fonttools:fonttools:4.33.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.33.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.33.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.33.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.33.2:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.33.2:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.33.3:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.33.3:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.34.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.34.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.34.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.34.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.34.2:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.34.2:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.34.3:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.34.3:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.34.4:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.34.4:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.35.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.35.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.36.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.36.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.37.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.37.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.37.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.37.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.37.2:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.37.2:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.37.3:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.37.3:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.37.4:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.37.4:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.38.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.38.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.39.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.39.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.39.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.39.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.39.2:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.39.2:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.39.3:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.39.3:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.39.4:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.39.4:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.40.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.40.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.41.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.41.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.41.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.41.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.42.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.42.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.42.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.42.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.43.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.43.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.43.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.43.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.44.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.44.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.44.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.44.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.44.2:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.44.2:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.44.3:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.44.3:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.45.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.45.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.45.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.45.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.46.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.46.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.47.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.47.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.47.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.47.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.47.2:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.47.2:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.48.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.48.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.48.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.48.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.49.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.49.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.50.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.50.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.51.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.51.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.52.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.52.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.52.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.52.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.52.2:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.52.2:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.52.3:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.52.3:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.52.4:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.52.4:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.53.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.53.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.53.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.53.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.54.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.54.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.54.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.54.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.55.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.55.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.55.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.55.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.55.2:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.55.2:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.55.3:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.55.3:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.55.4:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.55.4:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.55.5:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.55.5:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.55.6:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.55.6:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.55.7:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.55.7:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.55.8:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.55.8:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.56.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.56.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.57.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.57.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.58.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.58.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.58.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.58.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.58.2:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.58.2:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.58.3:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.58.3:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.58.4:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.58.4:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.58.5:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.58.5:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.59.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.59.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.59.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.59.1:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.59.2:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.59.2:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.60.0:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.60.0:*:*:*:*:python:*:*
  • cpe:2.3:a:fonttools:fonttools:4.60.1:*:*:*:*:python:*:*
    cpe:2.3:a:fonttools:fonttools:4.60.1:*:*:*:*:python:*:*

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