MediumVulnerabilityLLM-specific

CVE-2025-51859: Chaindesk stored cross-site scripting in agent chat component

Source: NVD(opens in a new tab)
Identifier: CVE-2025-51859
Published: July 22, 2025
Record updated: October 9, 2026

Known exploitation: Not listed in the CISA Known Exploited Vulnerabilities catalog at the last check.
EPSS: 0.5%

Summary

CVE-2025-51859 is a stored Cross-Site Scripting (XSS) flaw in the agent chat component of Chaindesk through 2025-05-26. An attacker can craft an AI agent whose system prompt instructs the underlying Large Language Model (LLM) to embed script payloads, such as SVG-based XSS, in its chat responses. When a user interacts with that agent or opens a direct link to a conversation containing the payload, the script runs in the user's browser, which can expose sensitive data such as JWT session tokens and enable account hijacking.

Mitigation

The source does not state a fix yet. Check the original advisory for updates.

Details

Scores and exploitation

CVSS score: 6.5(medium)
EPSS: 0.5%Estimated probability that this CVE is exploited in the next 30 days, from the FIRST Exploit Prediction Scoring System. Read on November 4, 2026.

Weaknesses and techniques

Weakness (CWE): CWE-79
Attack pattern (CAPEC): CAPEC-198
CAPEC-86
AI threat technique (MITRE ATLAS): AML.T0051

Classification

Attack type: Prompt injection,
Other
Attack sophistication: Moderate
AI component targeted: Agent
Impact: Confidentiality,
Integrity
Labels: security

How this record was produced

Summaries, mitigations and labels on this page are generated automatically from the source. The linked source is authoritative. The source gives this advisory a description and no title, so the title above is a headline generated from the source text.

Original source: https://nvd.nist.gov/vuln/detail/CVE-2025-51859

First tracked: February 15, 2026 at 08:53 PM ET, from NVD/CVE Database

Classifier: claude-haiku-5-5, prompt v4

Classifier confidence: 90% (self-assessed)

Summary

Mitigation

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