CVE-2026-34560: CI4MS: Logs Full Account Takeover for All-Roles & Privilege-Escalation via Stored DOM XSS

Should you act?

Critical, preconditions apply

Severe if exploited, but exploitation needs conditions that may not apply to you. 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 0.5%, percentile 39: FIRST’s model estimates a 0.5% chance of exploitation activity in the next 30 days, higher than 39% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Needs an account (low (any account)). 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 renders user-controlled input unsafely within the logs interface. If any stored XSS payload exists within logged data, it is rendered without proper output encoding. This issue becomes a Blind XSS scenario because the attacker does not see immediate execution. Instead, the payload is stored within application logs and only executes later when an administrator views the logs page. This issue has been patched in version 0.31.0.0.

From the GitHub advisory

Summary Vulnerability: Stored DOM Blind XSS via Logs Interface Rendering (Administrative Context Execution) - Stored Cross-Site Scripting (Blind XSS) via Unsafe Rendering of User-Controlled Logged Data

Description The application renders user-controlled input unsafely within the logs interface. If any stored XSS payload exists within logged data, it is rendered without proper output encoding.

This issue becomes a Blind XSS scenario because the attacker does not see immediate execution. Instead, the payload is stored within application logs and only executes later when an administrator views the logs page.

For example, accessing /backend/backup/restore/xss-payload-here causes an error that gets logged by the application. If the injected portion contains an XSS payload, it is stored inside the logs without sanitization and later rendered unsafely inside the logs management interface.

When an administrator views the logs page, the stored payload executes automatically in the administrative browser context, leading to stored blind cross-site scripting (Blind XSS).

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: low (any account)
• User interaction: none
• Scope: changed (can affect other components)

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): 0.46% probability of exploitation activity in the next 30 days; percentile 39.

Timeline

• 2026-04-01 — CVE record published by GitHub_M
• 2026-04-01 — GitHub-reviewed advisory GHSA-r4v5-rwr2-q7r4 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-r4v5-rwr2-q7r4 github.com
2. CVE.org record CVE-2026-34560 cve.org
3. NVD entry CVE-2026-34560 nvd.nist.gov

Other references from the CVE record and advisory

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

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