S4E just found a high top 10 tcp port service scan
medium·Web Vulnerabilities·Updated Nov 10, 2025

CL.TE HTTP Request Smuggling Scanner

Detects 'HTTP Header Injection' vulnerability in Basic CL.TE - HTTP request smuggling.

Est. Time~10 seconds
Scan TypeSingle Scan
Targetsdomain, subdomain, ipv4
CostFree
0
Times Used
by S4E users
0
Assets Scanned
domains & IPs
0
Vulnerabilities Found
confirmed findings
References
Detail

In modern web development, HTTP protocol is frequently used to request and transfer resources across networked environments. Companies rely on the proper configuration of HTTP headers to maintain effective communication between clients and servers. The Basic CL.TE request smuggling vulnerability primarily affects HTTP headers, impacting the way servers parse incoming requests. This could lead to miscommunication, which could be used for various harmful attacks. It is essential for web administrators and developers to be aware of such vulnerabilities and have strategies in place to mitigate them.

The HTTP Header Injection vulnerability occurs when malicious actors inject undesirable data into request headers, leading servers to process data inadequately. This vulnerability can enable dangerous actions, like modifying headers or completely altering request behavior. Attackers can exploit header injection to conduct multiple types of attacks, including information disclosure or partial denial of service. Understanding this vulnerability is crucial for mitigating potential risks and safeguarding web resources.

The Basic CL.TE request smuggling vulnerability manipulates the Content-Length and Transfer-Encoding headers. This can cause disparate parsing results between a proxy and a backend server, leading servers to behave inconsistently. Attackers intercept or alter HTTP headers during transit, potentially injecting malicious content. This vulnerability is characterized by utilizing different interpretations of request headers like CL and TE, manipulating how server-side data is processed or forwarded. These technical discrepancies make it necessary for network managers to regularly audit and validate header configurations.

If exploited, this vulnerability can lead to numerous adverse effects. Malicious actors may execute unauthorized requests altering the state of the server unbeknownst to end-users. This can cause information leakage, resource consumption escalation, or even full server compromise. The effects can cripple a server's ability to manage resources effectively or provide a steady quality of service to users. For these reasons, HTTP request smuggling represents a significant risk to both safety and performance of web systems.

REFERENCES

Solution Advice
  • Regularly audit HTTP headers for inconsistent configurations to avoid discrepancies between different server interpretations.
  • Adopt standardized practices for HTTP header handling and mitigate any discrepancies between content-length and transfer-encoding directives.
  • Employ web application firewalls to monitor and filter potentially malicious HTTP requests.
  • Update server software to the latest release to mitigate known vulnerabilities related to HTTP header injection.
  • Conduct periodic security assessments to identify and rectify misconfigurations in server request handling.

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