How severe is CVE-2021-26812?

CVE-2021-26812 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which products are affected by CVE-2021-26812?

CVE-2021-26812 affects the following products: jitsi meet.

How do I patch CVE-2021-26812?

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.

How do I detect CVE-2021-26812 across my infrastructure?

Inventory every jitsi meet deployment and check each version against the affected-products list above.

How do I mitigate CVE-2021-26812 if there is no patch (or I can't update yet)?

Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.

Is CVE-2021-26812 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2021-26812, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-26812?

CVE-2021-26812 has an EPSS (Exploit Prediction Scoring System) score of 97.2%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

What type of vulnerability is CVE-2021-26812?

CVE-2021-26812 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

Which products and versions are affected by CVE-2021-26812?

CVE-2021-26812 affects jitsi meet. Check the affected-products list on this page against your deployed version to confirm exposure.

Is there exploit tooling available for CVE-2021-26812?

A Nuclei detection template exists for CVE-2021-26812, meaning automated scanners can fingerprint it. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2021-26812 published, and has it been updated?

CVE-2021-26812 was published on April 14, 2021 and was last updated on June 17, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🛡️

Not in CISA KEV

MEDIUM severity

CVE-2021-26812 — MEET

MEDIUM

CVE-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. No vendor fix is recorded yet; mitigation options are listed below.

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…

Published

Apr 14, 2021

Updated

Jun 17, 2026

Affected

1 product

Patched

See advisory

Exploits

1 known

Exploitation data as of Oct 29, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

97.2%probability of exploitation in next 30 days

Very High Risk0.00%

Lower risk than most CVEs100th percentile — riskier than 100% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-26812 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 397,508 CVEs with a current EPSS score, this one falls in the ≥ 90% band (highlighted). Counts from FIRST.org, log-scaled.

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

1 product · 1 configurations

Application

meetjitsi

≥ 2.7 && ≤ 2.8.3

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Cross Site Scripting (XSS) in the Jitsi Meet 2.7 through 2.8.3 plugin fo…

github.comNVDApr 2021

Detection & mitigation playbook

Vendor / appliance

Detect
Inventory every jitsi meet deployment and check each version against the affected-products list above.
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
Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.

How to detect CVE-2021-26812

A community-maintained Nuclei template exists for this CVE. You can scan for it directly:

nuclei -id cve-2021-26812 -u https://target

Template: Moodle Jitsi Meet 2.7-2.8.3 - Cross-Site Scripting
Severity: medium
Impact: Successful exploitation of this vulnerability could allow an attacker to execute arbitrary JavaScript code in the context of the victim's browser, leading to session hijacking, defacement, or theft of sensitive information.
Remediation: Update to the latest version of the Moodle Jitsi Meet plugin to mitigate the XSS vulnerability.

Template by ProjectDiscovery nuclei-templates (aceseven (digisec360)), MIT licensed. View the full template. Scan only systems you are authorised to test.

Frequently Asked Questions

O3 Security · Runtime Protection

Is CVE-2021-26812 being exploited in your environment?

Detect and block the exploit chain at execution, on systems you cannot patch yet.

Protect my workloads How runtime protection works

CVSS Score

6.1/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CWE Classification

CWE-79Cross-site Scripting (XSS)

Weaponization

Timeline

Disclosed

Apr 14, 2021

First exploit

Apr 21, 2021

7 days after disclosure — rapid exploitation

Last updated

Jun 17, 2026

Identifiers

CVE-2021-26812

References

Exploit / PoCgithub.com Exploit / PoCgithub.com

Related vulnerabilities

This CVE is medium severity; 8 of 8 other CVEs with CWE-79 are rated as high or higher (top: high).

CVE-2026-118246CVE-2026-118251CVE-2026-118253CVE-2026-116797CVE-2026-118244CVE-2026-118242CVE-2026-118255CVE-2026-118257Browse all CWE-79

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedJun 17, 2026