CVE-2025-66034
mediumfontTools 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.
6.3
cvss
medium
common vulnerability scoring system v3.1. measures intrinsic severity on a 0-10 scale.
epss
0.0012
kev
no
cisa known exploited vulnerabilities catalog. confirmed active exploitation.
CVSS 3.1
Common Vulnerability Scoring System v3.1
6.3
/ 10
MEDIUM
exploitability
Attack Vector
Local
Attack Vector (AV:L): requires local access. attacker must have shell access or physical login.
Attack Complexity
High
Attack Complexity (AC:H): exploitation requires specific conditions outside the attacker's control (race condition, non-default config, etc).
Privileges Required
None
Privileges Required (PR:N): no authentication needed. any anonymous attacker can exploit this.
User Interaction
Required
User Interaction (UI:R): victim must perform some action (e.g. clicking a link, opening a file).
impact
Scope
Changed
Scope (S:C): exploitation impacts resources beyond the vulnerable component.
Confidentiality
None
Confidentiality (C:N): no confidentiality impact.
Integrity
High
Integrity (I:H): complete data modification possible. attacker can modify any data.
Availability
Low
Availability (A:L): reduced performance or partial service interruption.
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:C/C:N/I:H/A:L
activity density
rdintel assessment
flagged malicious repos detected. do not execute.
public exploit available. prioritize patching.
detection rules available.
composite score from 15+ signals including exploitation status, epss probability, detection coverage, and community attention. 0-100 scale.
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