CVE-2026-34557

Vulnerability: Stored DOM XSS via Group / Role Management Fields (Administrative Context Execution)

• Stored Cross-Site Scripting via Unsanitized Group / Role Management Inputs

Description

The application fails to properly sanitize user-controlled input within group and role management functionality. Multiple input fields (three distinct group-related fields) can be injected with malicious JavaScript payloads, which are then stored server-side.

These stored payloads are later rendered unsafely within privileged administrative views without proper output encoding, leading to stored cross-site scripting (XSS) within the role and permission management context.

Affected Functionality

• Group creation and editing functionality
• Role and permission assignment interfaces
• Storage and retrieval of group-related data

Attack Scenario

• An attacker injects a malicious XSS payload into one or more group-related input fields.
• The application stores these values without sanitization or encoding.
• An administrator views the group or role management interface.
• The payload executes automatically in the administrator’s browser.

Steps To Reproduce (POC)

1. Navigate to the Group / Role Management page
2. Insert an XSS payload into any of the three group-related input fields such as:
   <img src=x onerror=alert(document.domain)>
3. Save the group or role changes
4. View the group/role management page as an administrator
5. Observe the XSS payload executing automatically

Ready Video POC:

https://mega.nz/file/6QUEXDbR#JXzYXg9bef_NeSUVFB4R03UeXLtAVtYwTRsdrHLlokU

• Persistent Stored XSS
• Execution of arbitrary JavaScript in victims’ browsers
• Privilege escalation when viewed by administrators
• Full administrator account takeover
• Full compromise of the entire application

Endpoints:

• /backend/users/groupList/

Untrusted input is rendered as active markup in a victim's browser, which can run script in their session. Typical impact: session or credential theft, and actions taken as the user.

CVE-2026-34557 has a CVSS score of 9.1 (Critical). The vector is network-reachable, low privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (0.31.0.0); upgrading removes the vulnerable code path.

Kodem intelligence

• Never use .html() again or any innerHTML-style like JS in your PHP, or any other sink, even if user inputs that flow into them are not clear, they still represent real world danger as an attacker can make use of this to exploit the application via XSS. And do HTML Encoding as much as possible and always do Sanitization, theres no sanitization there unfortunately. Also apply CSP, HttpOnly, SameSite, and Secure upon all application, they reduce severity of XSS & escalated-CSRF via XSS and do great jobs

1. What is CVE-2026-34557? CVE-2026-34557 is a critical-severity cross-site scripting (XSS) vulnerability in ci4-cms-erp/ci4ms (composer), affecting versions <= 0.28.6.0. It is fixed in 0.31.0.0. Untrusted input is rendered as active markup in a victim's browser, which can run script in their session.
2. How severe is CVE-2026-34557? CVE-2026-34557 has a CVSS score of 9.1 (Critical). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
3. Which versions of ci4-cms-erp/ci4ms are affected by CVE-2026-34557? ci4-cms-erp/ci4ms (composer) versions <= 0.28.6.0 is affected.
4. Is there a fix for CVE-2026-34557? Yes. CVE-2026-34557 is fixed in 0.31.0.0. Upgrade to this version or later.
5. Is CVE-2026-34557 exploitable, and should I be worried? Whether CVE-2026-34557 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
6. What actually determines whether CVE-2026-34557 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
7. How do I fix CVE-2026-34557? Upgrade ci4-cms-erp/ci4ms to 0.31.0.0 or later.