CVE-2026-21866Disclosure(dify / dify)

MEDIUMCVSS 5.4 · MEDIUM

Exploitation ongoing with high activity in latest observed window (1 mentions)

Immediate actions

Patch dify dify systems immediately
Assume compromise if assets are exposed

Recommended action window: Immediate (within 24h)

NVD description

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.

dify CVEs Back to dashboard

4.0/ 10 priority

Sources & remediation

Patch / fix

Exploit / PoC references

https://github.com/langgenius/dify/security/advisories/GHSA-qpv6-75c2-75h4

Weakness type (CWE)

CWE-79

Priority

MEDIUM

Exploitation

ACTIVE

PoC

YES

Patch

AVAILABLE

Momentum

STABLE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

dify

Threat summary

Active exploitation appears in 1 classified signals
Patch or workaround signal is available
4 mentions across 3 observed days
Momentum state: stable

What's happening

Active exploitation reported across 1 signal
Patch or workaround mentioned in 1 signal
Technical details provided in 4 signals
Disclosure: 3 classified signals
Peaked 2d ago at 2 mentions (2026-03-03); latest day: 1
4 total mentions across 3 days

Affected systems

Vendors

dify

Products

dify

Deep dive

Activity timeline4 mentions / 3d

Signal classification2 categories

Disclosure

375.0%

Active Exploitation

125.0%

Referenced assets4 URLs

By indicator

Classification over time

Date	Total	Labels

2026-03-03	2	Disclosure2
2026-03-04	1	Disclosure1
2026-06-22	1	Active Exploitation1

Full discourse4 posts

Aviatrix Threat Research Center@aviatrixtrc109d
Active Exploitation
TRC analysis shows attackers exploited authorization bypasses in Dify's multi-tenant AI platform to access private conversations across all tenants using only file UUIDs. The flaws (CVE-2026-41949, CVE-2026-21866) demonstrate how weak tenant isolation can turn single compromises into cross-customer data exposure. #CloudSecurity 🔗 Full TRC analysis: https://aviatrix.ai/threat-research-center/researchers-detail-difytap-flaws-in-dify-that-could-expose-ai-chats-across-tenants
Post summary
Attackers have successfully used CVE-2026-41949 and CVE-2026-21866 to bypass authorization in Dify’s multi‑tenant AI platform, enabling cross‑tenant data exposure.
0001072
1.9K followersView on X
Vulmon Vulnerability Feed@VulmonFeeds220d
Disclosure
CVE-2026-21866 Stored XSS in Dify LLM Platform via Mermaid Diagram Rendering Prior to 1.11.2 https://vulmon.com/vulnerabilitydetails?qid=CVE-2026-21866
Post summary
The text discloses a stored XSS vulnerability (CVE-2026-21866) affecting Dify LLM Platform before version 1.11.2 through Mermaid diagram rendering.
0001067
4.0K followersView on X
Infoflowcloud@infoflowcloud220d
Disclosure
🚨*CVE* CVE-2026-21866 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 occu… https://www.cve.org/CVERecord?id=CVE-2026-21866 ----- Traducción: CVE-2026-21866 Dif… http://infoflow.cloud`
Post summary
The post announces CVE-2026-21866, a stored XSS vulnerability in Dify’s Mermaid diagram rendering, but provides no PoC, exploit, or patch details.
0000042
55 followersView on X
CVE@CVEnew220d
Disclosure
CVE-2026-21866 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 occu… https://www.cve.org/CVERecord?id=CVE-2026-21866
Post summary
Dify versions before 1.11.2 are vulnerable to a stored XSS flaw via Mermaid diagrams in chats, and the issue is presumably addressed in the 1.11.2 release.
00000199
56.6K followersView on X

CPE platform detail1 entries

Part:

Vendor:

Product:

Version:

Target SW:

Target HW:

1 of 1 entries

Part	Vendor	Product	Version	Target SW	Target HW
App	dify	dify	-	-	-

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What researchers are saying

CVE-2026-21866

Aviatrix Threat Research Center[verified]@aviatrixtrcActive Exploitation

Attackers have successfully used CVE-2026-41949 and CVE-2026-21866 to bypass authorization in Dify’s multi‑tenant AI platform, enabling cross‑tenant data exposure.

Vulmon Vulnerability Feed@VulmonFeedsDisclosure

The text discloses a stored XSS vulnerability (CVE-2026-21866) affecting Dify LLM Platform before version 1.11.2 through Mermaid diagram rendering.

Infoflowcloud@infoflowcloudDisclosure

The post announces CVE-2026-21866, a stored XSS vulnerability in Dify’s Mermaid diagram rendering, but provides no PoC, exploit, or patch details.

CVE@CVEnewDisclosure

Dify versions before 1.11.2 are vulnerable to a stored XSS flaw via Mermaid diagrams in chats, and the issue is presumably addressed in the 1.11.2 release.