Critical Qt6 Vulnerability in Fedora 42 (CVE-2025-5455): Patch Guide & Security Implications

 

Fedora 42 users: A critical Qt6 vulnerability (CVE-2025-5455) threatens system stability. Learn how to patch via DNF, understand the denial-of-service risks, and protect your Linux environment. Includes CVE references, update instructions, and security best practices.

1. Security Alert: Critical Qt6 Vulnerability in Fedora 42

A high-severity flaw (CVE-2025-5455) in Qt 6.9.1, a core component of Fedora 42’s GUI framework, has been identified. 

This assertion failure bug in QtCore can trigger denial-of-service (DoS) attacks, compromising system stability. Red Hat has classified this as a critical update, urging immediate patching.

Why This Matters:

• Qt6 underpins thousands of Linux applications, including KDE Plasma and multimedia tools.

• Unpatched systems risk crashes, data loss, or exploitation in targeted attacks.

• Fedora’s rapid update cycle ensures fixes are available within 24 hours of disclosure.

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2. Patch Instructions: Secure Your System Now

Step-by-Step Update Guide

1. Terminal Command:

   bash

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   su -c 'dnf upgrade --advisory FEDORA-2025-c546fd3f09'

2. Verify Installation:

   bash

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   rpm -q qt6-translations

   Expected output: qt6-translations-6.9.1-1.fc42.

Alternative: Use GNOME Software or KDE Discover for GUI updates.

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3. Technical Deep Dive: Qt6 Vulnerabilities

CVE-2025-5455 (QtCore DoS)

• Impact: Maliciously crafted inputs crash applications using Qt6’s core libraries.

• Affected Modules: QtCore, QtTranslations.

• Related CVE: CVE-2025-5683 (Qt5 ICNS image crash).

Mitigation:

• Apply updates immediately; no known workarounds exist.

• Monitor Red Hat Bugzilla for emergent threats.

4. Why Qt6 Security Affects You

Qt6 is the backbone of:

• Enterprise software (e.g., CAD tools, medical imaging).

• Consumer apps (e.g., VLC, Telegram Desktop).

• Critical infrastructure (embedded systems, kiosks).

5. Frequently Asked Questions (FAQ)

Q1. Can I delay this update?

A: No. DoS vulnerabilities are low-complexity exploits—often weaponized within days.

Q2. Does this affect Qt5?

A: Indirectly. See CVE-2025-5683 for Qt5 risks.

Q3. How to audit Qt6 dependencies?

A:

bash

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dnf repoquery --requires qt6-common

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6. Conclusion & Next Steps

Fedora’s proactive security model minimizes exposure, but user action is critical.

• Patch now using the DNF command above.

• Bookmark Red Hat Security Advisories.