CVE-2026-43876
MediumWhat is CVE-2026-43876?
WWBN AVideo is an open source video platform. In versions up to and including 29.0, objects/notifySubscribers.json.php takes the raw message POST parameter and passes it into sendSiteEmail(), which substitutes it directly into an HTML email template (via str_replace on the {message} placeholder) and renders it with PHPMailer::msgHTML(). There is no HTML sanitization, character escaping, or output encoding on the attacker-controlled message between $_POST['message'] and the rendered email. Any authenticated user with upload permission can therefore broadcast arbitrary HTML — phishing links, tracking pixels, CSS/UI spoofing — to every subscriber on their channel (up to 10,000 recipients per invocation). The email is sent From: the platform's configured contact address and wrapped in the site's official logo and title, so attacker-supplied HTML arrives with the appearance of an official platform communication. Commit https://github.com/WWBN/AVideo/commit/ contains an updated fix.
CVSS Vector Breakdown
CVSS 3.1Exploitable remotely over the network without requiring access to the local system.
No special conditions required. Exploit can be performed reliably and repeatedly.
Basic user account required (e.g. standard login without admin rights).
No user interaction required. Exploit runs without any victim action.
Exploiting the vulnerability can affect other components beyond the vulnerable one.
Some sensitive information is disclosed, but attacker has limited access.
Attacker can modify some data, but scope or consequence is limited.
No availability impact. Service remains fully operational.
FAQ
CVE-2026-43876 has a CVSS score of 6.4/10, rated as Medium. Review the affected products list and apply vendor patches.
CVSS (Common Vulnerability Scoring System) rates vulnerability severity from 0.0 to 10.0. CVE-2026-43876 scores 6.4/10 (Medium). Scores 9.0–10.0 are Critical, 7.0–8.9 are High, 4.0–6.9 are Medium, and below 4.0 are Low.
The list of devices confirmed to be affected by CVE-2026-43876 is shown in the "Affected Devices" section above. Check your firmware version against the vendor security advisory and apply the latest patch.
Apply the latest firmware or software update from the vendor. Check the References section above for official advisories and patch notes. If no patch is available, consider disabling the affected feature or isolating the device from untrusted networks.