CVE-2019-16645 in GoAhead
Summary
by MITRE
An issue was discovered in Embedthis GoAhead 2.5.0. Certain pages (such as goform/login and config/log_off_page.htm) create links containing a hostname obtained from an arbitrary HTTP Host header sent by an attacker. This could potentially be used in a phishing attack.
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Analysis
by VulDB Data Team • 05/26/2025
The vulnerability identified as CVE-2019-16645 affects Embedthis GoAhead web server version 2.5.0 and represents a significant security flaw that can be exploited for phishing attacks. This issue stems from the improper handling of HTTP Host headers within specific administrative pages of the web server software. The vulnerability specifically impacts pages such as goform/login and config/log_off_page.htm which are designed to construct hyperlinks containing hostnames retrieved directly from attacker-controlled HTTP Host headers. This behavior creates a dangerous scenario where malicious actors can manipulate the hostname portion of URLs that appear in authentication and logout pages, potentially deceiving users into believing they are interacting with legitimate systems.
The technical implementation of this vulnerability involves the web server's failure to properly sanitize or validate the Host header value before incorporating it into generated hyperlinks. When an attacker sends a crafted HTTP request with a malicious Host header, the GoAhead server processes this value and embeds it directly into the HTML output of sensitive pages. This creates a scenario where users who visit these pages may see links that appear to lead to trusted internal systems but actually direct them to attacker-controlled domains. The flaw essentially allows for the injection of malicious hostnames into legitimate-looking administrative interfaces, exploiting the trust users place in familiar login and logout screens.
The operational impact of this vulnerability extends beyond simple phishing attempts to potentially enable more sophisticated attack vectors. An attacker can leverage this flaw to create convincing fake login pages that appear to be part of the legitimate web application, thereby tricking users into entering credentials or other sensitive information. The vulnerability particularly affects administrative interfaces where users expect to see trusted hostnames in navigation links, making it more likely that victims will not question the legitimacy of the embedded URLs. This type of attack can be particularly effective in corporate environments where users are accustomed to seeing specific hostnames in their internal systems and may not recognize the subtle deception.
This vulnerability aligns with CWE-79, which describes Cross-Site Scripting (XSS) conditions where untrusted data is incorporated into web pages without proper validation or encoding. The flaw also corresponds to ATT&CK technique T1566.001, which involves phishing attacks through spearphishing with links, as the malicious hostnames can be used to create deceptive links that direct users to attacker-controlled resources. The attack vector specifically targets the trust relationship between users and web applications, exploiting the expectation that authentication and logout pages will contain legitimate hostnames. Organizations using Embedthis GoAhead 2.5.0 should immediately implement mitigations including input validation for Host headers, proper URL encoding in generated links, and regular updates to address this vulnerability. The flaw demonstrates the importance of validating all user-supplied input, particularly in contexts where such input becomes part of web page content, as it can create opportunities for attackers to manipulate user perception and potentially compromise security controls.