CVE-2026-48907

This vulnerability lets a person on the internet break into a Joomla site’s JCE editor feature without needing an account. Once they do, they can upload malicious files and make the server run them as PHP code—like leaving a “back door” that turns into full control of the site.

This matters if you run a Joomla website using the Joomla Content Editor (JCE) extension and your JCE version is older than 2.9.99.5.

Because the flaw is remote and does not require login, it’s especially risky for sites that are reachable from the internet. The practical risk is highest when the vulnerable JCE component is installed and reachable through normal site requests; CISA is treating it as an actively exploited target.

RED: Attackers are actively exploiting this flaw in the wild, and CISA has added it to its Known Exploited Vulnerabilities list.

You have a near-term deadline from CISA (mitigation due by 2026-06-19), and the fix is available by upgrading to the fixed JCE version.

1. Confirm exposure on your site

   • Log into your Joomla admin and check which extensions are installed.
   • Locate the installed version of the Joomla Content Editor (JCE) extension.
   • Determine whether the site is publicly reachable (typical production sites are) and whether JCE is enabled.

2. Determine whether you’re affected

   • You are affected if your JCE version is older than 2.9.99.5.

3. Upgrade to the fixed version

   • Upgrade JCE to version 2.9.99.5.
   • Use the official JCE update/upgrade process from the vendor guidance referenced in the findings.
   • Note: Joomla guidance emphasizes that updating “closes the entry point” but does not automatically clean a site if it was already compromised—so plan follow-up checks after updating.

4. If you were already compromised (or you can’t confirm)

   • Treat the site as potentially compromised because exploitation is confirmed and automated.
   • Use Joomla’s indicators of compromise (IoCs) provided by the vendor (as referenced in the findings) to look for signs of uploaded/created malicious files.
   • Review relevant web server and Joomla logs around the exploitation timeframe and check for unexpected new files in web-accessible directories associated with the compromise.

5. Follow CISA timing

   • CISA listed this in KEV on 2026-06-16 with a remediation due date of 2026-06-19; align your update and validation work to meet that date.

6. What to monitor after patching

   • Re-check that the JCE entry point is updated correctly and remains enabled only as needed.
   • Continue scanning for unexpected files and unusual application behavior shortly after the upgrade, since attackers may have already established persistence before patching.

Severity is critical (CISA and active exploitation). CVE-2026-48907 is a CWE-284 (improper access control) issue in the Joomla Content Editor (JCE) extension.

Mechanism: an unauthenticated attacker can create new editor profiles; this improper access control then leads to PHP code upload and execution on the server.

Exploitation status: confirmed active exploitation reported in 2026-06-17, with automated attacks and working exploit code reported publicly; CISA added the vulnerability to its Known Exploited Vulnerabilities catalog (added 2026-06-16) and set a remediation due date of 2026-06-19.

Fix: JCE is fixed in 2.9.99.5. CISA expects mitigations aligned with vendor instructions and, where mitigations are unavailable, discontinuation of use; stakeholders should assess internet exposure per CISA BOD 26-04 guidance. (No need to rely on predictions for urgency here because KEV/real-world exploitation is confirmed.)