CVE-2026-108725: Cheshire Cat AI core through 2.0.23 Stored XSS via uploads plugin

Severity: medium (CVSS 5.4 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-11 · updated 2026-10-16
Weakness: CWE-79

Description

Cheshire Cat AI core through 2.0.23 contains a stored cross-site scripting vulnerability in the uploads plugin that allows authenticated users to upload HTML files via POST /uploads without type restrictions. Attackers can send 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.

Affected products

cheshire-cat-ai core: through 2.0.23

References

https://github.com/cheshire-cat-ai/core
https://github.com/cheshire-cat-ai/core/blob/c22731e7009ac89835b1d7b1cabc5989d998ec3e/src/cat/scaffold/plugins/uploads/endpoints.py#L28-L96
https://hackmd.io/@haind03/cheshire-cat-uploads-stored-html-same-origin-xss
https://www.vulncheck.com/advisories/cheshire-cat-ai-core-through-2.0.23-stored-xss-via-uploads-plugin
https://hackmd.io/@haind03/cheshire-cat-uploads-stored-html-same-origin-xss

Get alerted when CVE-2026-108725 or the next vulnerability affects your stack