Overview
CVE-2026-34443 describes an SSRF vulnerability in FreeScout, a Laravel-based PHP application. Prior to FreeScout v1.8.211, the helper function checkIpByMask() only attempted CIDR checks when the input string contained a slash ('/'). Plain IP addresses such as 10.0.0.1 do not include '/', so the function would skip CIDR validation entirely. As a result, the private address spaces 10.0.0.0/8 and 172.16.0.0/12 could be used to induce SSRF, allowing an attacker to make the server request internal endpoints or services that should be inaccessible from the application. This behavior effectively left critical internal resources exposed to SSRF payloads and could lead to data exfiltration, internal service access, or lateral movement from the compromised host.
In exploitation terms, an attacker could leverage outbound requests initiated by the Laravel app (for example, fetching resources, hitting internal APIs, or contacting internal metadata endpoints) by supplying a target that resolves to a private IP address. Since the vulnerable code path only validates CIDR inputs and ignores plain IPs, the SSRF barrier never triggers for plain IP targets, enabling direct access to private infrastructure. This aligns with the CVE description and CWE-918 (Server-Side Request Forgery).
Remediation involves reworking the input validation to treat IPs and CIDRs uniformly, and to explicitly reject private/public-private mappings that should never be used to reach internal resources. The fix should be implemented in real Laravel code by validating the input as an IP, extracting a base IP from any CIDR, and checking against a robust set of private ranges for IPv4 (and private ranges for IPv6 where applicable). Upgrade to the patched version (FreeScout v1.8.211) or apply a targeted patch that performs strict IP/CIDR validation and denies private addresses for SSRF-prone code paths. Additionally, add tests to cover both plain IP and CIDR inputs and investigate outbound request configurations in the Laravel Http client or curls to ensure no private ranges are reachable.
Affected Versions
FreeScout <= 1.8.210 (prior to 1.8.211)
Code Fix Example
Laravel API Security Remediation
Vulnerable:
<?php
class Helper {
// Vulnerable: only checks CIDR when the input includes '/'. Plain IPs are never validated
public static function checkIpByMask($ip) {
if (strpos($ip, '/') !== false) {
foreach (['10.0.0.0/8','172.16.0.0/12','192.168.0.0/16'] as $range) {
if (self::ipInCidr($ip, $range)) {
return true;
}
}
return false;
}
return false;
}
private static function ipInCidr($ip, $cidr) {
[$net, $bits] = explode('/', $cidr);
$ipLong = ip2long($ip);
$netLong = ip2long($net);
$mask = -1 << (32 - (int)$bits);
return ($ipLong & $mask) === ($netLong & $mask);
}
}
?>
Fixed:
<?php
class Helper {
public static function checkIpByMask($ip) {
$base = $ip;
if (strpos($ip, '/') !== false) {
$base = explode('/', $ip, 2)[0];
}
if (filter_var($base, FILTER_VALIDATE_IP) === false) {
return false;
}
// IPv4: block private ranges explicitly
if (filter_var($base, FILTER_VALIDATE_IP, FILTER_FLAG_IPV4)) {
$l = ip2long($base);
if (($l >= ip2long('10.0.0.0') && $l <= ip2long('10.255.255.255')) ||
($l >= ip2long('172.16.0.0') && $l <= ip2long('172.31.255.255')) ||
($l >= ip2long('192.168.0.0') && $l <= ip2long('192.168.255.255')) ||
($l >= ip2long('127.0.0.0') && $l <= ip2long('127.255.255.255'))) {
return false;
}
return true;
}
// IPv6: basic private range check fc00::/7 (ULA) or loopback; adjust policy as needed
if (filter_var($base, FILTER_VALIDATE_IP, FILTER_FLAG_IPV6)) {
if (strpos($base, ':') !== false && (strpos($base, 'fc') === 0 || strpos($base, 'fd') === 0)) {
return false;
}
return true;
}
return false;
}
}
?>