CVE-2021-26812
MEDIUMCVE-2021-26812 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in jitsi meet. 1 public exploit reference exists, so weaponization risk is real. O3 Security detects and blocks CVE-2021-26812 exploitation at runtime via eBPF exploit-chain detection and L7 egress monitoring, even on unpatched systems.
Cross Site Scripting (XSS) in the Jitsi Meet 2.7 through 2.8.3 plugin for Moodle via the "sessionpriv.php" module. This allows attackers to craft a malicious URL, which when clicked…
Description
Cross Site Scripting (XSS) in the Jitsi Meet 2.7 through 2.8.3 plugin for Moodle via the "sessionpriv.php" module. This allows attackers to craft a malicious URL, which when clicked on by users, can inject javascript code to be run by the application.
Affected Products
meetjitsiResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
Detection & mitigation playbook
Vendor / applianceDetect
Inventory every jitsi meet deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.
Remediation status
No patch has shipped for CVE-2021-26812 yet — track the jitsi meet advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.
How O3 protects you
O3 detects and blocks CVE-2021-26812 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.
Tailored to CVE-2021-26812. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2021-26812 being exploited in your environment?
O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2021-26812 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.