Raw vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:LCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-34566 is a critical-severity Cross-site Scripting (CWE-79) vulnerability in Ci4-Cms-Erp Ci4Ms. Its CVSS base score is 9.1 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Browser Session Hijacking (T1185); ranked at the 19th 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 map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-34566 is a stored DOM-based cross-site scripting (XSS) vulnerability (CWE-79) in CI4MS, a CodeIgniter 4-based CMS skeleton providing production-ready modular architecture with RBAC authorization and theme support. Prior to version 0.31.0.0, the Page Management functionality fails to properly sanitize user-controlled input during page creation or editing. Multiple input fields accept attacker-controlled JavaScript payloads that are stored server-side and later rendered without adequate output encoding in administrative page lists and public-facing page views. The vulnerability carries a CVSS v3.1 base score of 9.1 (AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:L).
Low-privileged authenticated users with access to create or edit pages can exploit this issue over the network with low complexity and no user interaction required. By injecting malicious JavaScript payloads into vulnerable input fields, attackers can achieve stored XSS that executes in the context of administrative interfaces and public pages. This enables high-impact confidentiality breaches, such as session hijacking or data exfiltration, alongside low-impact integrity and availability effects due to the changed scope.
The issue has been addressed in CI4MS version 0.31.0.0, as detailed in the project's GitHub release notes (https://github.com/ci4-cms-erp/ci4ms/releases/tag/0.31.0.0) and security advisory (https://github.com/ci4-cms-erp/ci4ms/security/advisories/GHSA-458r-h248-29c5). Security practitioners should upgrade to the patched version and review existing pages for potentially malicious content, applying output encoding where necessary.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-18080
Vulnerability Data
CI4MS is a CodeIgniter 4-based CMS skeleton that delivers a production-ready, modular architecture with RBAC authorization and theme support. Prior to version 0.31.0.0, the application fails to properly sanitize user-controlled input within the Page Management functionality when creating or editing…
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pages. Multiple input fields accept attacker-controlled JavaScript payloads that are stored server-side. These stored values are later rendered without proper output encoding across administrative page lists and public-facing page views, leading to stored DOM-based cross-site scripting (XSS). This issue has been patched in version 0.31.0.0.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V1.1.2V1.3.2
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation can discover missing or incorrect input neutralization through targeted web-application tests.
Input validation directly enforces neutralization of untrusted data before it reaches web output generation.
Output filtering can catch or sanitize unneutralized script content before it is served to users.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly target introduction of XSS via coding standards/testing (mostly), yet the single broad outcome leaves many specific neutralization vectors unaddressed (partial).
Patching and EOL replacement can remediate known XSS instances in libraries or frameworks (partial) but do nothing to enforce input neutralization in application code (none).
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Knowledge exchange on emerging attack techniques and patches reduces the likelihood that cross-site scripting flaws remain unaddressed in deployed applications.
Operational indicators of compromise for web-application attacks can be incorporated into WAF or input-filtering rules, lowering the likelihood that unsanitized data reaches the browser.
Requiring language-specific secure-coding standards and automated scanning during the SDLC catches missing output encoding or improper neutralization of untrusted data before the software reaches production.
Secure-coding standards, SAST scans and removal of insecure code samples together eliminate the failure to neutralize script content that produces cross-site scripting flaws.
Secure-coding testing and automated code-analysis tools are applied to detect improper neutralization of script-related content during web-page generation.