CVE-2026-22421
Published: 05 March 2026
Summary
CVE-2026-22421 is a high-severity PHP Remote File Inclusion (CWE-98) vulnerability. Its CVSS base score is 8.1 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 39.1th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-22421 is an Improper Control of Filename for Include/Require Statement in PHP Program vulnerability, classified as PHP Remote File Inclusion but enabling PHP Local File Inclusion (CWE-98), in the Quantum WordPress theme developed by AncoraThemes. This issue affects all versions of the Quantum theme from n/a through 1.0 inclusive. The vulnerability was published on 2026-03-05 and carries a CVSS v3.1 base score of 8.1 (AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H), indicating high severity due to network accessibility despite high attack complexity.
Unauthenticated remote attackers can exploit this vulnerability over the network without requiring user interaction. Exploitation allows high-impact compromise of confidentiality, integrity, and availability, typically through local file inclusion to access sensitive files or, in certain configurations, achieve remote code execution via PHP inclusion mechanisms.
Mitigation details are provided in the Patchstack advisory at https://patchstack.com/database/Wordpress/Theme/quantum/vulnerability/wordpress-quantum-theme-1-0-local-file-inclusion-vulnerability?_s_id=cve.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-9550
Vulnerability details
Improper Control of Filename for Include/Require Statement in PHP Program ('PHP Remote File Inclusion') vulnerability in AncoraThemes Quantum quantum allows PHP Local File Inclusion.This issue affects Quantum: from n/a through <= 1.0.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Unauthenticated remote LFI vulnerability in a public-facing WordPress theme directly enables exploitation of a public-facing web application.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
SI-2 requires timely identification, reporting, and remediation of flaws, directly addressing the PHP local file inclusion vulnerability in the Quantum WordPress theme by applying patches or updates.
SI-10 mandates information input validation and error handling, preventing exploitation of improper filename controls in PHP include/require statements used in this LFI vulnerability.
SI-9 enforces restrictions on information inputs by type, pattern, or content, blocking malicious filenames supplied by unauthenticated attackers targeting the file inclusion mechanism.