CVE-2026-34565 — ci4-cms-erp/ci4ms
CRITICALCVE-2026-34565 is a critical-severity (CVSS 9.1) Cross-site Scripting (XSS) vulnerability in ci4-cms-erp/ci4ms. A fix is available for ci4-cms-erp/ci4ms — see the affected versions and patch details below.
CI4MS: Menu Management (Posts) Full Account Takeover for All-Roles & Privilege-Escalation via Stored DOM XSS
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-34565.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2026-34565 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
ci4-cms-erp/ci4msReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Vulnerability: Stored DOM XSS via Posts Added to Menu (Persistent Payload Injection)
- Stored Cross-Site Scripting via Unsafe Rendering of Post Entries in Menu Management
Description
The application fails to properly sanitize user-controlled input when adding Posts to navigation menus through the Menu Management functionality. Post-related data selected via the Posts section is stored server-side and rendered without proper output encoding.
These stored values are later rendered unsafely within administrative dashboards and public-facing navigation menus, resulting in stored DOM-based cross-site scripting (XSS).
Affected Functionality
- Menu Management – Posts section
- Adding posts to navigation menus
- Menu storage and rendering logic
Attack Scenario
- An attacker creates or controls a post containing a malicious JavaScript payload.
- The attacker adds the post to the menu using the Posts functionality in Menu Manager.
- The application stores the menu entry without sanitization or encoding.
- The payload persists and executes whenever the menu is rendered.
Impact
- Persistent Stored DOM XSS
- Execution of arbitrary JavaScript in victims’ browsers
- Privilege escalation in administrative contexts
- Full administrator account takeover
- Full account takeover across all roles
- Full compromise of the entire application via global navigation execution
Endpoint:
/backend/menu/
Steps To Reproduce (POC)
- Navigate to Menu Management
- Use the Posts section to add a post containing an XSS payload such as:
<img src=x onerror=alert(document.domain)> - Save the menu
- View the menu in the administrative panel or any public-facing page
- Observe the JavaScript payload executing automatically
Remediation
-
Avoid unsafe DOM manipulation methods: Do not use
.html(),innerHTML, or similar sink functions in client-side JavaScript or server-side templating (e.g., PHP). Even when user input flowing into these sinks is not immediately apparent, they can introduce Cross-Site Scripting (XSS) vulnerabilities that an attacker may exploit. -
Apply output encoding: Implement HTML entity encoding on all user-controlled data before rendering it in the browser. This helps neutralize potentially malicious input.
-
Implement input sanitization: Ensure that all user-supplied input is properly sanitized before processing or output. Currently, no sanitization mechanisms are in place, which should be addressed as a priority.
-
Enforce security headers and cookie attributes:
- Content Security Policy (CSP): Define and enforce a strict CSP to limit the execution of unauthorized scripts.
- HttpOnly flag: Set the
HttpOnlyattribute on session cookies to prevent client-side script access. - SameSite attribute: Configure the
SameSitecookie attribute to mitigate Cross-Site Request Forgery (CSRF) risks. - Secure flag: Ensure all cookies are transmitted only over HTTPS by enabling the
Secureattribute.
These measures collectively reduce the impact of XSS and help prevent escalation paths such as CSRF via XSS.
Ready Video POC:
https://mega.nz/file/PcMiUA5K#L2RlZJa340Q8K42TksxiXMuo_9XsRYPi14-WvBnak2A
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | ci4-cms-erp/ci4ms | all versions | 0.31.0.0composer require ci4-cms-erp/ci4ms:^0.31.0.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for ci4-cms-erp/ci4ms, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update ci4-cms-erp/ci4ms to 0.31.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-34565 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-34565 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-34565. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-34565 in your dependencies?
O3 Security finds CVE-2026-34565 across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.