CVE-2025-12385 is a vulnerability classified under CWE-770 (Allocation of Resources Without Limits or Throttling) and CWE-1284 (Improper Validation of Specified Quantity in Input) affecting The Qt Company's Qt framework across Windows, MacOS, Linux, iOS, Android, and multiple CPU architectures (x86, ARM, 64-bit, 32-bit). The flaw resides in the Qt Quick Text component's handling of the <img> tag, where the width and height attributes are not properly validated. This lack of validation allows an attacker to specify excessively large dimensions, causing the application to allocate excessive memory or other resources without limits or throttling. The consequence is that the affected application can become unresponsive or crash, effectively resulting in a denial-of-service (DoS) condition. The vulnerability affects a broad range of Qt versions from 5.0.0 through 6.5.10, 6.6.0 through 6.8.5, and 6.9.0 through 6.10.0, indicating a long-standing issue across multiple releases. The CVSS 4.0 base score is 8.7 (high), reflecting the vulnerability's network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), and high impact on availability (VA:H). No known exploits have been reported in the wild yet, but the vulnerability's characteristics make it a prime candidate for exploitation in denial-of-service attacks. The vulnerability is particularly concerning for applications that render user-supplied or external content using Qt Quick Text components, as malicious actors could craft inputs that trigger excessive resource consumption remotely and without authentication.

For European organizations, the impact of CVE-2025-12385 can be significant, especially for those relying on Qt-based applications in critical sectors such as finance, telecommunications, automotive, healthcare, and industrial control systems. The vulnerability can lead to application unavailability or crashes, disrupting business operations and potentially causing service outages. This is particularly critical for real-time or safety-critical systems where application responsiveness is essential. The broad platform and architecture support of Qt mean that many types of devices and endpoints could be affected, increasing the attack surface. Additionally, organizations developing software products using Qt may face reputational damage and increased support costs if their applications are vulnerable. The lack of required authentication and user interaction means attackers can exploit this remotely and at scale, increasing the risk of widespread denial-of-service attacks. While no exploits are currently known, the high CVSS score and ease of exploitation suggest that threat actors may develop exploits soon, emphasizing the need for proactive mitigation.

1. Monitor The Qt Company's official channels for patches addressing CVE-2025-12385 and apply updates promptly once available. 2. Until patches are released, implement input validation and sanitization at the application level to restrict the width and height attributes in <img> tags to reasonable limits, preventing excessive resource allocation. 3. Employ application-layer resource throttling and timeout mechanisms to detect and mitigate unusually large or malformed inputs that could trigger the vulnerability. 4. Use runtime monitoring and anomaly detection tools to identify unusual memory or CPU usage patterns indicative of exploitation attempts. 5. For organizations developing Qt-based applications, review and harden the code handling user-supplied content, especially in UI components rendering images or external content. 6. Consider deploying Web Application Firewalls (WAFs) or network-level filters to block or rate-limit suspicious traffic targeting vulnerable endpoints. 7. Conduct security testing and fuzzing focused on the Qt Quick Text component to identify and remediate similar input validation issues proactively. 8. Educate developers and security teams about this vulnerability to ensure awareness and readiness to respond to potential exploitation attempts.