CVE-2026-108725 cheshire-cat-ai CVE debrief

Who should care

Defenders responsible for Cheshire Cat AI core deployments, administrators, and security teams should assess exposure and verify the effectiveness of current security controls against stored cross-site scripting attacks.

Why it matters

Defenders should prioritize verifying exposure of Cheshire Cat AI core versions up to 2.0.23 and assessing the effectiveness of current security controls against stored cross-site scripting attacks.

• Execution of script in the application origin with the victim's access_token cookie
• Potential for authenticated users to upload malicious HTML files
• Possible exploitation through public GET /uploads/{path} URL
• Verification of security controls against stored cross-site scripting attacks

Technical summary

The Cheshire Cat AI core through 2.0.23 contains a stored cross-site scripting vulnerability in the uploads plugin. Authenticated users can upload HTML files via POST /uploads without type restrictions. Attackers can exploit this by sending the public GET /uploads/{path} URL to a signed-in victim, executing script in the application origin with the victim's access_token cookie, including administrators.

Defensive priority

Defenders should prioritize verifying exposure of Cheshire Cat AI core versions up to 2.0.23 and assessing the effectiveness of current security controls against stored cross-site scripting attacks.

Recommended defensive actions

• Verify exposure of Cheshire Cat AI core versions up to 2.0.23
• Assess the effectiveness of current security controls against stored cross-site scripting attacks
• Implement restrictions on file uploads to prevent HTML file uploads without proper validation
• Monitor for suspicious activity and update to a fixed version when available
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and source item provide details on a stored cross-site scripting vulnerability in the uploads plugin of Cheshire Cat AI core through 2.0.23. The vulnerability allows authenticated users to upload HTML files without type restrictions, which can be exploited by sending a public GET URL to a signed-in victim, executing script in the application origin with the victim's access_token cookie.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.