Description

The Ajaxify Comments WordPress plugin before 3.2 is vulnerable to HTTP Header Injection due to insufficient input sanitization and output escaping on user-supplied data. This makes it possible for unauthenticated attackers to inject arbitrary HTTP headers.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "5.4",
  "pubDate": "2026-09-02T15:17:38.270Z",
  "pubdate": "2026-09-02T15:17:38.270Z",
  "executiveSummary": "The Ajaxify Comments WordPress plugin before version 3.2 is susceptible to an HTTP Header Injection vulnerability. This flaw arises from inadequate input sanitization and improper output escaping of user-supplied data before it is included in HTTP response headers.\nThe vulnerability allows unauthenticated remote attackers to inject arbitrary HTTP headers into the application response. Successful exploitation can lead to a variety of malicious outcomes, including the hijacking of user sessions via Set-Cookie injection, the bypass of Cross-Site Scripting (XSS) filters, or the redirection of users to malicious websites via Cache-Poisoning or Header-based redirection techniques.\nGiven that the vulnerability does not require authentication, the risk level is high. Attackers can execute this attack by crafting malicious requests targeting the vulnerable plugin components. Organizations utilizing Ajaxify Comments below version 3.2 are advised to treat this as a critical security concern due to the ease of exploitation and the potential for severe impact on the integrity and security of the web application communication channel.",
  "technicalDetails": "The vulnerability resides in the way the Ajaxify Comments plugin handles dynamic data transmitted through client requests. The root cause is identified as the application's failure to sanitize user-controllable input before incorporating said data into the response headers. This lack of strict validation allows an attacker to inject carriage return (CR, %0d) and line feed (LF, %0a) characters into the header stream.\nBy manipulating these characters, an attacker can terminate the existing header block and introduce new, unauthorized headers. For instance, an attacker could inject 'Set-Cookie: session_id=malicious_value' to perform session fixation attacks or force the browser to execute unintended behavior by injecting security policy headers that relax browser protections. Because these headers are reflected directly by the server in response to the crafted request, the attacker can influence the security context of the victim's session.\nThe attack flow proceeds as follows: First, the attacker identifies the input parameters within the Ajaxify Comments plugin that are reflected in the HTTP headers. Second, the attacker crafts a malicious payload containing newline sequences followed by the desired header fields. Third, this payload is sent as part of an HTTP GET or POST request to the web server. Fourth, the server, failing to strip or sanitize the newline sequences, treats the injected text as legitimate HTTP header directives. Finally, the server sends these headers back to the client, where the browser interprets the injected headers as legitimate server-side directives.\nThe affected versions are strictly those prior to 3.2. This vulnerability is accessible over the network without the requirement for administrative privileges or authenticated access. The impact of such an injection is significant, as it can be used to bypass Same-Origin Policy (SOP) restrictions, influence cache mechanisms to serve malicious content to other users (Web Cache Poisoning), or facilitate Cross-Site Scripting (XSS) via the manipulation of Content-Type or Content-Security-Policy headers. The technical exposure is limited to the server's response handling logic within the Ajaxify Comments codebase, which fails to enforce strict data filtering protocols."
}