CVE-2025-55420
Published: 21 August 2025
Summary
CVE-2025-55420 is a high-severity Cross-site Scripting (CWE-79) vulnerability in Foxcms Foxcms. Its CVSS base score is 8.8 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 45.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified are NIST 800-53 SI-10 (Information Input Validation) and SI-15 (Information Output Filtering).
Deeper analysis
CVE-2025-55420 is a reflected Cross-Site Scripting (XSS) vulnerability in the /index.php component of FoxCMS version 1.2.6. The flaw occurs when a crafted script is sent via a GET request, which is reflected unsanitized into the HTML response. This enables execution of arbitrary JavaScript code when a logged-in user submits or processes the malicious input. The vulnerability is associated with CWE-79 and carries a CVSS v3.1 base score of 8.8 (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H).
Any network-accessible attacker can exploit this vulnerability with low attack complexity and no privileges required, though it depends on user interaction from a logged-in victim. By tricking the target into accessing a malicious URL or submitting crafted input, the attacker can execute arbitrary JavaScript in the victim's browser context within the FoxCMS application. This could lead to high impacts, including theft of session data, account takeover, or further site compromise, given the elevated confidentiality, integrity, and availability effects.
Mitigation details are available in the referenced advisory at https://www.notion.so/FoxCMS-V1-2-6-Reflected-XSS-in-index-php-2222b2fd021080589d27ef8e1b9ebd86?source=copy_link, published on 2025-08-21.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-25450
Vulnerability details
A Reflected Cross Site Scripting (XSS) vulnerability was found in /index.php in FoxCMS v1.2.6. When a crafted script is sent via a GET request, it is reflected unsanitized into the HTML response. This permits execution of arbitrary JavaScript code when…
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a logged-in user submits the malicious input.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Reflected XSS in public-facing web app directly enables exploitation via T1190 and arbitrary JS execution via T1059.007.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
SI-15 directly prevents reflected XSS by requiring filtering of HTML outputs to sanitize crafted scripts reflected from GET requests in /index.php responses.
SI-10 enforces validation of GET request inputs to block malicious scripts before they are processed and reflected by FoxCMS /index.php.
SI-2 mandates identification and remediation of the specific flaw in FoxCMS v1.2.6 that allows unsanitized script reflection, preventing exploitation.