main/streams/xp_socket.c in PHP 7.x before 2017-03-07 misparses fsockopen calls, such as by interpreting fsockopen('127.0.0.1:80', 443) as if the address/port were 127.0.0.1:80:443, which is later truncated to 127.0.0.1:80. This behavior has a security risk if the explicitly provided port number (i.e., 443 in this example) is hardcoded into an application as a security policy, but the hostname argument (i.e., 127.0.0.1:80 in this example) is obtained from untrusted input.
Severity
CVSS 3.0
7.5 high
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS
2.4% chance of exploitation in the next 30 days; higher than 84% of CVEs (scores of 2026-10-31)