CVE-2025-25193 in netty
Summary
by MITRE • 02/11/2025
Netty, an asynchronous, event-driven network application framework, has a vulnerability in versions up to and including 4.1.118.Final. An unsafe reading of environment file could potentially cause a denial of service in Netty. When loaded on an Windows application, Netty attempts to load a file that does not exist. If an attacker creates such a large file, the Netty application crash. A similar issue was previously reported as CVE-2024-47535. This issue was fixed, but the fix was incomplete in that null-bytes were not counted against the input limit. Commit d1fbda62d3a47835d3fb35db8bd42ecc205a5386 contains an updated fix.
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Analysis
by VulDB Data Team • 01/23/2026
The vulnerability identified as CVE-2025-25193 affects Netty, a widely-used asynchronous network application framework that serves as the foundation for numerous high-performance network applications and microservices architectures. This issue specifically targets versions up to and including 4.1.118.Final, making it a significant concern for organizations that rely on Netty for their network communication infrastructure. The vulnerability stems from an unsafe reading mechanism when processing environment files, creating a potential denial of service condition that could severely impact system availability and operational continuity. The flaw manifests particularly when Netty is executed within Windows applications, where the framework attempts to load a file that does not exist, creating a path for malicious exploitation.
The technical implementation of this vulnerability involves an incomplete fix for a previously reported issue CVE-2024-47535, which demonstrates the complexity of addressing security flaws in network frameworks. When an attacker deliberately creates a large file that triggers the file loading mechanism, the Netty application experiences a crash due to improper handling of the file reading process. The root cause lies in the insufficient input validation where null-bytes are not properly accounted for against the established input limits, allowing malicious inputs to bypass security controls. This particular weakness in the validation mechanism creates a scenario where attackers can craft specifically sized files that will cause the application to consume excessive resources or directly crash, effectively rendering the service unavailable to legitimate users.
From an operational perspective, this vulnerability represents a critical threat to system stability and availability, particularly in environments where Netty is used for mission-critical network services. The denial of service impact can be severe as it affects not just individual applications but potentially entire service architectures that depend on Netty's event-driven communication model. The vulnerability's exploitation requires minimal technical expertise, making it accessible to threat actors with basic knowledge of file system manipulation and network application behavior. Organizations running affected versions of Netty face the risk of service disruption, potential data loss, and reputational damage if these vulnerabilities are not addressed promptly. The issue is particularly concerning in cloud-native environments where Netty is commonly used for service-to-service communication in containerized applications and microservices architectures.
The remediation approach for CVE-2025-25193 requires immediate upgrading to a patched version of Netty that includes the updated fix referenced in commit d1fbda62d3a47835d3fb35db8bd42ecc205a5386. Organizations should prioritize this update as part of their vulnerability management processes, ensuring that all instances of Netty are upgraded to versions that properly account for null-bytes in input validation. Security teams should conduct thorough testing of the updated versions in staging environments to ensure compatibility with existing applications and prevent unintended side effects. Additionally, implementing network monitoring and intrusion detection systems can help identify potential exploitation attempts, while access controls should be reviewed to limit who can create or modify files that might trigger this vulnerability. This vulnerability aligns with CWE-129 and CWE-131 categories related to input validation and buffer overflow conditions, and it maps to ATT&CK techniques involving denial of service and privilege escalation through application-level vulnerabilities.