CVE-2025-58056 is a low-severity vulnerability affecting Netty, an asynchronous event-driven network application framework. The vulnerability arises from an incorrect implementation that allows standalone newline characters (LF) to be accepted as chunk-size line terminators, contrary to the HTTP/1.1 standards that require a preceding carriage return (CR). This improper handling can lead to request smuggling attacks when utilized in conjunction with reverse proxies that interpret LF differently, treating it as part of the chunk extension.
The vulnerability is present in versions 4.1.124.Final and 4.2.0.Alpha3 through 4.2.4.Final. The risk to organizations includes potential unauthorized access or manipulation of HTTP requests, which could compromise the integrity of network communications. Patching to versions 4.1.125.Final and 4.2.5.Final is vital to mitigate this vulnerability.
While the exploitability is assessed as low, the implications of request smuggling can be significant, especially for applications heavily reliant on HTTP communication. Organizations should prioritize reviewing their Netty deployments and ensure they are running patched versions to maintain secure operations.
Given that this vulnerability has not been actively exploited in the wild, organizations should still address it as part of their routine security measures. Organizations should schedule remediation in their patch cycle to ensure they do not remain vulnerable.
Vulnerability Details
This vulnerability allows for the potential of request smuggling. The affected product is Netty, specifically within versions 4.1.124.Final and 4.2.0.Alpha3 through 4.2.4.Final. The publication date of the vulnerability was September 3, 2025, and it is classified under CWE-444.
Technical Analysis
The root cause of CVE-2025-58056 is a failure to comply with the HTTP/1.1 chunked transfer encoding specification, which mandates CRLF (carriage return followed by line feed) as the line terminator. By accepting LF as a valid terminator, Netty inadvertently allows attackers to craft requests that can be interpreted differently by reverse proxies, leading to request smuggling.
The attack vector is network-based, requiring no special privileges or user interaction. The attack complexity is low, making it feasible for attackers to exploit this vulnerability in environments using Netty as a server framework. Confidentiality impact is none, while integrity impact is classified as low, indicating that while unauthorized modifications can occur, the overall information confidentiality is maintained.
Risk & Impact Analysis
The potential risks associated with CVE-2025-58056 include unauthorized request manipulation and the possibility of service disruption. In practical terms, organizations using Netty may expose themselves to vulnerabilities that could be exploited to bypass security controls or manipulate data flows. Even though this vulnerability is rated as low, organizations should not underestimate the implications of request smuggling, especially in high-traffic applications.
Organizations should prioritize patching immediately to avoid any possible exploitation, as even low-severity vulnerabilities can be leveraged in conjunction with other weaknesses to achieve significant impact.
Signal | Status |
|---|---|
Known Exploit | No |
Public PoC | No |
Actively Exploited | No |
Ransomware Use | No |
Affected Versions
The affected versions of Netty include 4.1.124.Final and 4.2.0.Alpha3 through 4.2.4.Final. Organizations should upgrade to versions 4.1.125.Final or 4.2.5.Final to eliminate this vulnerability.
Mitigation & Remediation
To remediate CVE-2025-58056, organizations should prioritize updating to the fixed versions of Netty: 4.1.125.Final and 4.2.5.Final. If immediate patching is not feasible, consider implementing workarounds such as adjusting configurations on reverse proxies to handle chunked transfer encoding more securely.
Additionally, organizations should conduct thorough monitoring of network traffic to detect any anomalous behavior indicative of potential exploitation attempts. For those looking to enhance their security posture further, investing in penetration testing services can help identify vulnerabilities before they are exploited.
Detection Guidance
Organizations should monitor logs for indications of irregular HTTP request patterns that may suggest attempts at request smuggling. Specific log entries that show chunked transfer encoding anomalies should be flagged for further investigation.
AppSecure Threat Intelligence Insight
CVE-2025-58056 illustrates the importance of adhering to protocol specifications in application development. Security teams should take this opportunity to review their dependency management and ensure that all components are kept up to date. The trend of vulnerabilities related to improper parsing and handling of input data highlights the need for rigorous testing practices.
To learn more about strengthening your security practices, consider reviewing our vulnerability management program design and our comprehensive penetration testing methodology guide to enhance your security posture.
As we continue to observe developments in security vulnerabilities, it's essential for organizations to remain vigilant and proactive in their defense strategies.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
.webp)