PHP 8.x fsockopen Null Char Validation Flaw <8.1.33/8.2.29/8.3.23/8.4.10
CVE-2025-1220 Published on July 13, 2025
Null byte termination in hostnames
In PHP versions:8.1.* before 8.1.33, 8.2.* before 8.2.29, 8.3.* before 8.3.23, 8.4.* before 8.4.10 some functions like fsockopen() lack validation that the hostname supplied does not contain null characters. This may lead to other functions like parse_url() treat the hostname in different way, thus opening way to security problems if the user code implements access checks before access using such functions.
Vulnerability Analysis
CVE-2025-1220 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is consided to have a high level of attack complexity. Public availability of a proof of concept (POC) exploit exists for CVE-2025-1220. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a small impact on integrity and availability.
Weakness Type
What is a SSRF Vulnerability?
The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination. By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.
CVE-2025-1220 has been classified to as a SSRF vulnerability or weakness.
Products Associated with CVE-2025-1220
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Affected Versions
PHP Group PHP:- Version 8.1.* and below 8.1.33 is affected.
- Version 8.2.* and below 8.2.29 is affected.
- Version 8.3.* and below 8.3.23 is affected.
- Version 8.4.* and below 8.4.10 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.