CVE-2026-34561: CI4MS: System Settings (Social Media Management) Full Platform Compromise & Full Account Takeover for All-Roles & Privilege-Escalation via Stored DOM XSS

Should you act?

Normal patch cycle

No exploitation signal; fix it in your next routine update if you are affected. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.4%, percentile 27: FIRST’s model estimates a 0.4% chance of exploitation activity in the next 30 days, higher than 27% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Needs an account (high (admin)). Exposure depends on who can log in.
• Only applies if your dependency tree includes ci4-cms-erp/ci4ms (Composer (PHP)) <= 0.28.6.0, fixed in 0.31.0.0. Check your lockfile, including transitive dependencies.

What it is

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 System Settings – Social Media Management. Multiple configuration fields, including Social Media and Social Media Link, accept attacker-controlled input that is stored server-side and later rendered without proper output encoding. This issue has been patched in version 0.31.0.0.

From the GitHub advisory

Summary Vulnerability: Stored DOM XSS via System Settings – Social Media Management (Same-Page Attribute Breakout & Persistent Payload Injection) - Stored Cross-site Scripting via Unsanitized Social Media Configuration Fields with Immediate Same-Page Execution

Description The application fails to properly sanitize user-controlled input within System Settings – Social Media Management. Multiple configuration fields, including Social Media and Social Media Link, accept attacker-controlled input that is stored server-side and later rendered without proper output encoding.

Unlike typical stored XSS that executes on other pages (such as public-facing landing pages), this vulnerability executes directly on the same settings page. The injected payload breaks out of the input attribute context and is immediately interpreted by the browser, resulting in same-page DOM-based XSS.

This represents a different functionality and a separate vulnerability class from public-facing landing page injection.

Affected Functionality - System Settings – Social Media Management configuration - Same-page rendering of user-controlled input fields - DOM attribute injection within form inputs - Storage and retrieval of social media configuration values

Weakness type: CWE-79.

Product: ci4-cms-erp/ci4ms (Composer (PHP)) · Assigned by: GitHub_M · Published: 2026-04-01

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Privileges required: high (admin)
• User interaction: none
• Scope: unchanged

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable no, technical impact partial.
• FIRST EPSS (model of 2026-10-21): 0.35% probability of exploitation activity in the next 30 days; percentile 27.

Timeline

• 2026-04-01 — CVE record published by GitHub_M
• 2026-04-01 — GitHub-reviewed advisory GHSA-gcfj-cf7j-vwgj published (critical)
• 2026-04-02 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-gcfj-cf7j-vwgj github.com
2. CVE.org record CVE-2026-34561 cve.org
3. NVD entry CVE-2026-34561 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com

Critical Composer (PHP) advisories · Today’s Security Digest