What is the CVSS score of CVE-2026-21866?

CVE-2026-21866 has a CVSS 3.1 base score of 5.4 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N. EPSS exploitation probability: 0.0%.

Which versions of AI / ML are affected by CVE-2026-21866?

Organizations using Dify should be aware of moderate risk from CVE-2026-21866, a cross-site scripting vulnerability rated CVSS 5.4.. A patch is available.

Is there a public PoC exploit available for CVE-2026-21866?

Yes, a public proof-of-concept exploit is available for CVE-2026-21866. Prioritise patching immediately. EPSS: 0.0%.

AI / ML CVE-2026-21866

MEDIUM

Cross-site Scripting (XSS) (CWE-79)

2026-03-03 security-advisories@github.com

XSS AI / ML Dify

5.4

CVSS 3.1

CVSS VectorNVD

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

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 22:05 vuln.today

PoC Detected

Mar 05, 2026 - 21:24 vuln.today

Public exploit code

Patch released

Mar 05, 2026 - 21:24 nvd

Patch available

CVE Published

Mar 03, 2026 - 22:16 nvd

MEDIUM 5.4

DescriptionNVD

Dify is an open-source LLM app development platform. Prior to 1.11.2, Dify is vulnerable to a stored XSS issue when rendering Mermaid diagrams within chats. This occurs because Dify’s default Mermaid configuration uses securityLevel: loose, which allows potentially unsafe content to execute. This vulnerability is fixed in 1.11.2.

AnalysisAI

Dify versions prior to 1.11.2 contain a stored cross-site scripting vulnerability in Mermaid diagram rendering due to insecure default security configurations, allowing authenticated attackers with user interaction to inject and execute malicious scripts with cross-site impact. Public exploit code exists for this vulnerability, affecting users and developers of the Dify LLM application development platform. …

RemediationAI

Within 30 days: Identify affected systems and apply vendor patches as part of regular patch cycle. Verify Content-Security-Policy and output encoding.

Analysis

Detailed AI-generated intelligence summary covering attack vector, impact assessment, affected versions, remediation steps, and indicators of compromise.

POChttps://••••••••••.com/exploit

PATCHhttps://••••••••••.com/patch

ADVISORYhttps://••••••••••.com/advisory

Full analysis requires sign-in

Get intelligence summaries, risk assessment, exploit details, threat intel, and remediation guidance.

CVE-2026-21866 vulnerability details – vuln.today

Back