Overview

CVE-2025-55763 describes a critical buffer overflow vulnerability present in the URI parser of CivetWeb versions 1.14 through 1.16. This vulnerability can be exploited by a remote attacker to execute arbitrary code on the target system or cause a denial of service via a specially crafted HTTP request. It affects all systems running affected versions of CivetWeb, and due to its potential for system compromise and data leakage, it warrants immediate attention.

Vulnerability Summary

CVE ID: CVE-2025-55763
Severity: High (CVSS 7.5)
Attack Vector: Network
Privileges Required: None
User Interaction: None
Impact: May lead to system compromise, denial of service, or data leakage on successful exploitation

Affected Products

Product | Affected Versions

CivetWeb | 1.14 to 1.16 (inclusive)

How the Exploit Works

The vulnerability exists due to insufficient handling of input during the processing of HTTP requests by CivetWeb’s URI parser. A remote attacker can send a specially crafted HTTP request with an unusually long URI, causing a buffer overflow condition. This can corrupt heap memory, resulting in the execution of arbitrary code under the context of the application or cause the application to crash, leading to a denial of service.

Conceptual Example Code

A possible exploitation of the vulnerability might involve a POST request with a long URI, as shown in the conceptual example below:

POST /AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA... HTTP/1.1
Host: target.example.com
Content-Type: application/json
{ "malicious_payload": "..." }

Here, the long string of ‘A’s represents an unusually long URI used to trigger the buffer overflow.

Mitigation

End users are recommended to apply the latest vendor-supplied patches as soon as they are available. If a patch is not immediately available, using a Web Application Firewall (WAF) or Intrusion Detection System (IDS) can offer temporary mitigation by detecting and blocking crafted HTTP requests that attempt to exploit this vulnerability.