langgenius dify up to 1.11.1 Mermaid Diagram cross site scripting

CVSS Meta Temp Score
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CTI Interest Score
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4.4$0-$5k0.00

Summaryinfo

A vulnerability classified as problematic has been found in langgenius dify up to 1.11.1. Affected is an unknown function of the component Mermaid Diagram Handler. This manipulation causes cross site scripting. This vulnerability is registered as CVE-2026-21866. Remote exploitation of the attack is possible. No exploit is available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability has been found in langgenius dify up to 1.11.1 and classified as problematic. Affected by this vulnerability is some unknown processing of the component Mermaid Diagram Handler. The manipulation with an unknown input leads to a cross site scripting vulnerability. The CWE definition for the vulnerability is CWE-79. The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. As an impact it is known to affect integrity. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-21866 since 01/05/2026. The exploitation appears to be easy. The attack can be launched remotely. It demands that the victim is doing some kind of user interaction. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1059.007 according to MITRE ATT&CK.

Upgrading to version 1.11.2 eliminates this vulnerability. Applying the patch ae17537470bba417a8971fff705dd82ecb043564 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Vendor

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Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 4.4
VulDB Meta Temp Score: 4.4

VulDB Base Score: 3.5
VulDB Temp Score: 3.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 5.4
NVD Vector: 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Cross site scripting
CWE: CWE-79 / CWE-94 / CWE-74
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: dify 1.11.2
Patch: ae17537470bba417a8971fff705dd82ecb043564

Timelineinfo

01/05/2026 CVE reserved
03/04/2026 +58 days Advisory disclosed
03/04/2026 +0 days VulDB entry created
03/06/2026 +2 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: GHSA-qpv6-75c2-75h4
Status: Confirmed

CVE: CVE-2026-21866 (🔒)
GCVE (CVE): GCVE-0-2026-21866
GCVE (VulDB): GCVE-100-348655

Entryinfo

Created: 03/04/2026 04:41
Updated: 03/06/2026 04:07
Changes: 03/04/2026 04:41 (70), 03/06/2026 04:07 (11)
Complete: 🔍
Cache ID: 216::103

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