CVE-2021-21703
7.8 · HIGHOverview
CVE-2021-21703 is a high-severity vulnerability affecting php php. It was published on October 25, 2021 and has a CVSS 3.1 base score of 7.8 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.
Technical Description
In PHP versions 7.3.x up to and including 7.3.31, 7.4.x below 7.4.25 and 8.0.x below 8.0.12, when running PHP FPM SAPI with main FPM daemon process running as root and child worker processes running as lower-privileged users, it is possible for the child processes to access memory shared with the main process and write to it, modifying it in a way that would cause the root process to conduct invalid memory reads and writes, which can be used to escalate privileges from local unprivileged user to the root user.
Remediation
Check the references section for vendor advisories and patches from php. Update php to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| php | php | 7.3.0 | Affected |
| oracle | communications_diameter_signaling_router | 8.0.0.0 | Affected |
References
Frequently Asked Questions
What is CVE-2021-21703?
CVE-2021-21703 is a high-severity vulnerability affecting php php. It was published on October 25, 2021 and has a CVSS 3.1 base score of 7.8 (HIGH).
How severe is CVE-2021-21703?
This vulnerability has a CVSS 3.1 base score of 7.8, rated HIGH. It requires local or adjacent network access to exploit. Some level of privileges is required for exploitation.
How do I fix or remediate CVE-2021-21703?
Check the references section for vendor advisories and patches from php. Update php to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2021-21703?
CyberStrike's AI-powered security agents can automatically detect CVE-2021-21703 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
Automated penetration testing that runs continuously, not just quarterly.
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