DeepChat's Mermaid rendering has XSS leading to RCE
DeepChat is a smart assistant uses artificial intelligence. Prior to version 0.3.5, in the Mermaid chart rendering component, there is a risky operation of directly using `innerHTML` to set user content. Therefore, any malicious content rendered via Mermaid will directly trigger the exploit chain, leading to command execution. This vulnerability is primarily caused by a failure to fully address the existing XSS issue in the project, leading to another exploit chain. The exploit chain is consistent with the report GHSA-hqr4-4gfc-5p2j, executing arbitrary JavaScript code via XSS and arbitrary commands via exposed IPC. Version 0.3.5 contains an updated fix.
- Published
- Sep 9, 2025
- Updated
- Jun 17, 2026
- EPSS
- 0.6% · 47th percentile
- CWE
- CWE-94
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Report tools
Action score
38
Monitor
Low priority for now.
- CVSS
- 38 / 40 · 9.6 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.6%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · GitHub_M
- 9.7
- NVD has not scored this yet; the score shown is the CNA’s.
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| thinkinai | deepchat | cpe:2.3:a:thinkinai:deepchat |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- thinkinai deepchatbefore 0.3.5
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
ThinkInAIXYZ deepchat
- < 0.3.5affected
Same product
thinkinai: all recordsOther highest-scoring records for the same primary product.
- CVE-2025-67744Mermaid XSS vulnerability leads to Remote Code Execution38Monitor
- CVE-2025-66481DeepChat's Incomplete XSS Fix Allows RCE through Mermaid Content38Monitor
- CVE-2025-66222DeepChat Cross-Site Scripting(XSS) escalate to Remote Code Execution(RCE)38Monitor
- CVE-2025-55733DeepChat One-click Remote Code Execution through Custom URL Handling38Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2025-5573321 days apartDeepChat One-click Remote Code Execution through Custom URL Handling38Monitor
- CVE-2025-6622285 days apartDeepChat Cross-Site Scripting(XSS) escalate to Remote Code Execution(RCE)38Monitor
- CVE-2025-6774497 days apartMermaid XSS vulnerability leads to Remote Code Execution38Monitor
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- A user must open a link or visit a page.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
Impact can extend beyond the vulnerable component (scope changes).
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- Required
- Scope
- Changed
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-94 · Improper Control of Generation of Code ('Code Injection')CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.