How to fix CVE-2024-26503: openeclass (public exploit)

Unrestricted File Upload vulnerability in Greek Universities Network Open eClass v.3.15 and earlier allows attackers to run arbitrary code via upload of crafted file to certbadge.php endpoint.

• Severity: CRITICAL (CVSS 3.1 9.1, vector CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H).
• Weakness: CWE-434.
• NVD published 2024-03-14, status Analyzed.

Anyone running openeclass in the version ranges below. If the service is reachable from the internet, treat it as the priority.

• openeclass openeclass: up to and including 3.15.

Version ranges come from the NVD CPE configuration. Confirm against the vendor advisory before you rely on them.

• Exploit-DB: EDB-52698 Open eClass 3.15 - RCE (2026-10-21).

• EPSS (probability of exploitation activity in the next 30 days): 2.96%, higher than 87% of all scored CVEs (as of 2026-10-24).
• CVERadar threat level: 53/100 (see methodology).
• Likely ATT&CK techniques: T1190 Exploit Public-Facing Application (inferred); T1505.003 Web Shell (inferred).

1. Find every instance. List where openeclass runs, including test, DR and forgotten internet-facing systems, and record the installed version.
2. Apply the latest vendor update. NVD does not list a fixed version, so follow the vendor advisory for the patched release.
3. If you can't patch today, apply the vendor's workaround from the advisory, and take the service off the internet or restrict it to a VPN or allow-list until it is patched.
4. Verify the fix. Re-run the version check on every instance and confirm it reports the fixed build. Re-scan from outside if the service is exposed.
5. Hunt for signs of earlier compromise. If the system was exposed before you patched, assume it may have been hit and check the items below.
6. Rotate credentials stored on or used by the affected system if you cannot rule out compromise, and keep the logs you reviewed.

Detection hints

• T1190 Exploit Public-Facing Application: Review WAF, reverse-proxy and application logs for unusual requests to openeclass (odd paths, oversized or encoded payloads, bursts of errors), going back to at least 2024-03-14.
• T1505.003 Web Shell: Look for files added to web roots after the exposure window (web shells).

sudo find /var/www -type f \( -name "*.php" -o -name "*.jsp" -o -name "*.phtml" \) -mtime -30 -ls

Detection commands are generic starting points, not CVE-specific signatures. Use the indicators from the vendor advisory when it publishes them.

• NVD: CVE-2024-26503 nvd.nist.gov/vuln/detail/CVE-2024-26503
• CVE.org record www.cve.org/CVERecord?id=CVE-2024-26503
• FIRST EPSS (2026-10-24) api.first.org/data/v1/epss?cve=CVE-2024-26503