# CVE-2026-39393: Post-Installation Re-entry via Cache-Dependent Install Guard Bypass in ci4ms > Unauthenticated attackers can bypass the installation guard during cache misses to overwrite configuration files and take over the application. - **Severity:** High 8.1 (`CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Not needed - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 8 Apr 2026 - **Updated:** 10 Apr 2026 - **Also known as:** GHSA-8rh5-4mvx-xj7j ## What is CVE-2026-39393? CVE-2026-39393 is a high-severity authentication bypass vulnerability in ci4-cms-erp ci4ms, published on 8 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. ### Official description CI4MS is a CodeIgniter 4-based CMS skeleton that delivers a production-ready, modular architecture with RBAC authorization and theme support. Prior to 0.31.4.0, the install route guard in ci4ms relies solely on a volatile cache check (cache('settings')) combined with .env file existence to block post-installation access to the setup wizard. When the database is temporarily unreachable during a cache miss (TTL expiry or admin-triggered cache clear), the guard fails open, allowing an unauthenticated attacker to overwrite the .env file with attacker-controlled database credentials, achieving full application takeover. This vulnerability is fixed in 0.31.4.0. Weakness: CWE-306 (Missing Authentication for Critical Functionality) ## Which versions are affected by CVE-2026-39393? 2 open source packages ship an affected version, including ci4-cms-erp/ci4ms. It affects 1 product. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `ci4-cms-erp/ci4ms` | Packagist | All versions | 0.31.4.0 | | `ci4-cms-erp/ci4ms` | Packagist | All versions | 0.31.4.0 | Products: Ci4-Cms-Erp Ci4ms. ## How do I fix CVE-2026-39393? Upgrade ci4-cms-erp/ci4ms to 0.31.4.0 or later. ## Is CVE-2026-39393 being exploited? It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39393 exists. ## Other vulnerabilities in ci4-cms-erp ci4ms - [CVE-2026-34569](https://insights.sbomify.com/CVE-2026-34569/): CI4MS: Blogs Categories Full Account Takeover for All-Roles & Privilege-Escalation via Stored DOM XSS (critical 10.0) - [CVE-2026-34571](https://insights.sbomify.com/CVE-2026-34571/): CI4MS: Stored Cross‑Site Scripting (Stored XSS) in Backend User Management Allows Session Hijacking and Full Administrative Account Compromise (critical 10.0) - [CVE-2026-25510](https://insights.sbomify.com/CVE-2026-25510/): CI4MS Vulnerable to Remote Code Execution (RCE) via Arbitrary File Creation and Save in File Editor (critical 10.0) - [CVE-2026-34989](https://insights.sbomify.com/CVE-2026-34989/): CI4MS: Profile & User Management Full Account Takeover for All-Roles & Privilege-Escalation via Stored DOM XSS (critical 9.4) - [CVE-2026-34559](https://insights.sbomify.com/CVE-2026-34559/): CI4MS: Blogs Tags Full Account Takeover for All-Roles & Privilege-Escalation via Stored DOM XSS (critical 9.1) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2026-39393 and fix it if it is affected. What it is: CVE-2026-39393 is a high-severity authentication bypass vulnerability in ci4-cms-erp ci4ms, published on 8 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim. Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-39393 exists. Affected packages and fixed versions: - ci4-cms-erp/ci4ms (Packagist): affected all versions; fixed in 0.31.4.0 - ci4-cms-erp/ci4ms (Packagist): affected all versions; fixed in 0.31.4.0 Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2026-39393/ (Markdown: https://insights.sbomify.com/CVE-2026-39393/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2026-39393 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-39393 - OSV: https://osv.dev/vulnerability/CVE-2026-39393 --- From sbomify Insights: https://insights.sbomify.com/CVE-2026-39393/ Summaries are generated and may contain mistakes; the official description above is the record.