Fedora 42 Critical Security Update: Qt 6.9.1 Fixes Denial-of-Service Vulnerability in Qt6-QtSerialBus

 

Fedora 42 users: Critical Qt6-QtSerialBus DoS flaw (CVE-2025-5455) patched in Qt 6.9.1. Learn enterprise mitigation steps, update commands, and industrial IoT security best practices to protect CAN/ModBus systems.

Key Security Advisory for Linux Developers & Enterprise Users

A critical Denial-of-Service (DoS) vulnerability (CVE-2025-5455) has been patched in Qt 6.9.1, impacting Fedora 42 users relying on Qt6-QtSerialBus for industrial serial communication (CAN, ModBus, etc.). 

This update also addresses CVE-2025-5683, a separate Qt ICNS image processing flaw that could lead to system crashes.

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Update Details & Technical Breakdown

1. Vulnerability Analysis

• CVE-2025-5455: Assertion failure in QtCore triggers DoS via crafted serial bus packets.

• CVE-2025-5683: Memory corruption in Qt5 ICNS image handling (affects legacy systems).

2. Patch Implementation

Qt 6.9.1 resolves these issues. Fedora’s update includes:

bash

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Download

sudo dnf upgrade --advisory FEDORA-2025-c546fd3f09

For sysadmins: DNF upgrade guide

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Actionable Recommendations

For Developers

✅ Immediate Steps:

1. Patch all Fedora 42 systems using Qt6-QtSerialBus.

2. Audit industrial serial bus applications for unusual traffic.

For Enterprises

🔒 Premium Security Solutions:

• Network Segmentation: Isolate CAN/ModBus interfaces.

• Advanced Monitoring: Deploy Wireshark filters for malicious payloads.

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FAQ Section (Featured Snippet Optimization)

❓ Q: How does CVE-2025-5455 impact ModBus deployments?

A: Attackers can crash systems by sending malformed ModBus frames via unpatched Qt6-QtSerialBus instances.*

❓ Q: Is Qt5 still supported?

A: Limited updates only—migrate to Qt6 for long-term security.