MAL-2026-18271: Malicious code in fontus (PyPI)

Published Oct 25, 2026

Updated

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Source: amazon-inspector (bb5b8b4484126f787f9917d91b6815927146a308f64bfb852c57f5d60bf4bfbb) Analysis of fontus 0.0.3 on PyPI did not identify any code paths that exfiltrate installer data, execute attacker-controlled payloads at install or import time, relay caller-supplied data to third-party destinations, distribute live credentials, or establish persistence. No install-time network fetches, no lifecycle shell execution, no reads of credential paths (~/.aws, ~/.ssh, ~/.npmrc, browser profiles), and no obfuscated or dynamic-exec patterns were observed.

Source: kam193 (2a8fcff0fd4d827c6f174318ee41ea82eb2667c6d65349a01ca2215aa2f4dd5e) The package most likely performs fingerprinting by exfiltrating basic information and available fonts, with no other functionality.

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Category: PROBABLYPENTEST - Packages looking like typical pentest packages, but also anything that looks like testing, exploring pre-prepared kits, research & co, with clearly low-harm possibilities.

Campaign: 2026-10-fontus

Reasons (based on the campaign):

- The package contains code to exfiltrate basic data from the system, like IP or username. It has a limited risk.

Affected Software

1 affected component

pip/fontus=0.0.1, =0.0.2, =0.0.3

Event History

Oct 25, 2026

Advisory Published

via OSV·10:58 AM

Data Sourced

via OSV·10:58 AM

DescriptionAffected Software

Frequently Asked Questions

Is there evidence that installation or importing the package automatically runs an attacker-controlled payload?

The analysis of fontus 0.0.3 found no install-time network fetches, lifecycle shell execution, or code paths that execute attacker-controlled payloads at install or import time.

Does the available analysis indicate credential theft or persistence?

The analysis of fontus 0.0.3 found no reads of common credential locations, including ~/.aws, ~/.ssh, ~/.npmrc, or browser profiles, and found no live credentials or persistence mechanisms.

What is the reported malicious behavior, and how certain is it?

One source assesses the package as most likely fingerprinting systems by exfiltrating basic information and available fonts. However, a separate analysis of version 0.0.3 reported no identified data-exfiltration paths, so the supplied sources do not conclusively establish the behavior for that version.

MAL-2026-18271: Malicious code in fontus (PyPI)

Affected Software

Event History

Frequently Asked Questions

Is there evidence that installation or importing the package automatically runs an attacker-controlled payload?

Does the available analysis indicate credential theft or persistence?

What is the reported malicious behavior, and how certain is it?

Company

Resources

Contact

Frequently Asked Questions

Is there evidence that installation or importing the package automatically runs an attacker-controlled payload?

Does the available analysis indicate credential theft or persistence?

What is the reported malicious behavior, and how certain is it?